Binding protein derived from various parental proteins

Abstract

Binding proteins derived from parental protein that bind to a target. The binding proteins may bind to the target with a dissociation constant of 1 micromolar or less. The parental protein may have a variety of secondary structures and tertiary structures. Screening proteins and screening methos of screening the screening proteins.

Description

[0001] BINDING PROTEIN DERIVED FROM VARIOUS PARENTAL PROTEINS CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 531,655, filed August 9, 2023; U.S. Provisional Patent Application No.63 / 531,674 filed August 9, 2023; and U.S. Provisional Patent Application No. 63 / 531, 678 filed August 9, 2024, each of which is incorporated herein by reference in its entirety. GOVERNMENT FUNDING This invention was made with government support under EB023339, GM146372, GM008347, GM146372, and CA251600 awarded by the National Institutes of Health and GRFP-2237827 awarded by the National Science Foundation. The government has certain rights in the invention. SEQUENCE LISTING This application contains a Sequence Listing electronically submitted via Patent Center to the United States Patent and Trademark Office as an .xml file entitled “0110_000725WO01_ST26.xml” having a size of 217 kilobytes and created on August 7, 2024. The information contained in the Sequence Listing is incorporated by reference herein. SUMMARY The present disclosure describes binding proteins. The binding proteins may bind to a target with a dissociation constant of 1 micromolar or less. The binding proteins may be derived from a parental protein. The parental proteins may have a variety of secondary and tertiary structures. This disclosure describes, in one aspect, a binding protein derived from a parental protein having a three-helix bundle (α3). having an N-terminal region defining the N-terminus of the binding protein, a first alpha-helix, a second alpha-helix, a third alpha-helix, a C-terminal region defining the C-terminus of the binding protein, a first loop, and a second loop. The first alpha- helix is coupled to the N-terminal region, the first loop couples the first alpha-helix and the second alpha-helix, the second loop couples the second alpha-helix and the third alpha-helix, and the C-terminal region is coupled to the third alpha-helix. The parental protein further includes a first solvent-exposed surface that includes a first portion of the first alpha-helix. The parental protein further includes a second solvent-exposed surface that includes a first portion of the second alpha-helix. The parental protein further includes a third solvent-exposed surface that includes a second portion of the second alpha-helix and a first portion of the third alpha-helix. The parental protein further includes a fourth solvent-exposed surface that includes a second portion of the first alpha-helix and a third portion of the second alpha-helix. The parental protein further includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, at least a portion of the third solvent-exposed surface, or at least a portion of the fourth solvent-exposed surface. The binding protein differs from the parental protein by at least one residue within the binding region. The binding protein may bind to a target with a dissociation constant of one micromolar or less. In one or more embodiments, the parental protein having a three-helix bundle (α3) comprises the sequence Framework F (SEQ ID NO:1); Framework G (SEQ ID NO: 2), Framework H (SEQ ID NO: 3), Framework I (SEQ ID NO: 4), Framework J (SEQ ID NO:5), or Framework Consensus (SEQ ID NO:6). In one or more embodiments, the binding protein derived from the parental protein have a three-helix bundle comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences SEQ ID NO: 7 to SEQ ID NO: 30 (see Table 4). Each X in SEQ ID NO:7 to SEQ ID NO:30 can independently be any amino acid. In one or more embodiments, one or more of the Xs in a sequence can be A, C, D, G, N, S, T, or Y. In one or more embodiments, residue 17, residue 18, or both in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y. In one or more embodiments, one or more of the Xs in a sequence can be D, E, G, H, K, N, Q, R, or S. For example, in one or more embodiments, residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one more embodiments, residue 17 and residue 18 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y and residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one or more embodiments, one or more of the Xs in a sequence can be W. For example, in one or more embodiments, residue 43 of Con L1 (SEQ ID NO: 25), F L1 (SEQ ID NO: 26), G L1 (SEQ ID NO: 27), H L1 (SEQ ID NO: 28), I L1 (SEQ ID NO: 29), J L1 (SEQ ID NO: 30) is W. In one or more embodiments, the binding protein derived from the parental protein have a three-helix bundle comprises a sequence that has 90% or greater sequence identity to any of SEQ ID NO:31 to SEQ ID NO:53 (see Table 5). In one or more embodiments, the binding protein derived from the parental protein having a three-helix bundle has 35 amino acids to 50 amino acids. In one or more embodiments, the binding protein derived from the parental protein having a three-helix bundle has 40 amino acids to 50 amino acids. In one or more embodiments, the binding protein derived from the parental protein having a three-helix bundle has 40 amino acids to 45 amino acids. In another aspect, the present disclosure describes a binding protein derived from a parental protein having four beta-strands and one alpha-helix (β2αβ2). The parental protein includes a beta-sheet, an alpha-helix, a C-terminal portion, a first loop, a second loop, a third loop, and a fourth loop. The beta-sheet includes a first beta-strand, a second beta-strand, a third- beta strand, and a fourth beta-strand. In one or more embodiments, the first beta-strand defines the N-terminus of the binding protein. In other embodiments, the binding protein includes an N- terminal region that defines the N-terminus of the binding protein. In such embodiments, the N- terminal region is coupled to the first beta-strand. The first loop couples the first beta-strand and the second beta strand. The second loop couples the second beta-strand and the alpha-helix. The third loop couples the alpha-helix and the third beta strand. The fourth loop couples the third beta-strand and the fourth beta strand. The C-terminal portion defines the C-terminus of the binding protein and is coupled to the fourth beta-strand. The binding protein further includes a first solvent-exposed surface, a second solvent-exposed surface, and a third solvent-exposed surface. The first solvent-exposed surface includes a portion of the alpha-helix. The second solvent-exposed surface includes a portion the beta-sheet. The third solvent-exposed surface includes a portion of the first loop and a portion of the third loop. The binding protein includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, or at least a portion of the third solvent-exposed surface. The binding protein differs from the parental protein by at least one residue in the binding region. The binding protein may bind to a target with a dissociation constant of one micromolar or less. In one or more embodiments, the parental protein having four beta-strands and one alpha- helix comprises the sequence Framework A (SEQ ID NO: 67), Framework B (SEQ ID NO: 68), Framework C (SEQ ID NO: 69), Framework D (SEQ ID NO: 70), Framework E (SEQ ID NO: 71), or Framework Consensus Sequence (SEQ ID NO: 70). In one or more embodiments, the binding protein derived from the parental protein having four beta-strands and one alpha-helix comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences SEQ ID NO:73 to SEQ ID NO:102 (see Table 9). In some embodiments, one or more of the Xs in a sequence can be G or S. For example, in one or more embodiments, the fourth residue (first X residue) in A L2 (SEQ ID NO: 98), B L2 (SEQ ID NO: 99), C L2 (SEQ ID NO: 100, D L2 (SEQ ID NO: 101), or E L2 (SEQ ID NO: 102) can be G or S. In one or more embodiments, the binding protein derived from the parental protein having four beta-strands and one alpha-helix comprises a sequence that has 90% or greater sequence identity to any of SEQ ID NO:103 to SEQ ID NO:106 (see Table 10). In one or more embodiments, the binding protein derived from the parental protein having four beta-strands and one alpha-helix has 35 amino acids to 50 amino acids. In one or more embodiments, the binding protein derived from the parental protein having a three-helix bundle has 40 amino acids to 50 amino acids. In one or more embodiments, the binding protein derived from the parental protein having a three-helix bundle has 40 amino acids to 45 amino acids. In another aspect, the present disclosure describes a binding protein derived from a parental protein having three beta-strands and one alpha-helix. The parental protein includes an N-terminal region, a beta sheet, an alpha-helix, a first loop, a second loop, and a third loop. The beta sheet includes a first beta-strand coupled to the N-terminal region, a second beta-strand, and a third beta-strand defining the C-terminus of the protein. The first loop couples the first beta- strand and the alpha-helix. The second loop couples the alpha-helix and the second beta-strand. The third loop couples the second beta-strand and the third beta-strand. The parental protein further includes a first solvent-exposed surface that includes a portion of the beta sheet. The parental protein further includes a second solvent-exposed surface that includes a portion of the alpha-helix. The parental protein further includes a third solvent-exposed surface that includes at least a portion of the first loop and at least a portion of the third loop. The parental protein further includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, at least a portion of the third solvent- exposed surface, or any combination thereof. The binding protein differs from the parental protein by at least one residue within the binding region. The binding protein may bind to a target with a dissociation constant of one micromolar or less. In one or more embodiments, the parental protein having three beta-strands and one alpha-helix comprises the sequence Framework 1 (SEQ ID NO: 107), Framework 2 (SEQ ID NO:108), Framework 3 (SEQ ID NO:109), or Framework 4 (SEQ ID NO: 110) (see Table 13). In one or more embodiments, the binding protein derived from the parental protein having three beta-strands and one alpha-helix comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences SEQ ID NO:111 to SEQ ID NO:145 (see Table 14). Each X can independently be any amino acid. In one or more embodiments, the binding protein derived from the parental protein having three beta-strands and one alpha-helix comprise a sequence that has 90% or greater sequence identity to any of SEQ ID NO:143 to SEQ ID NO:183. In another aspect, the present disclosure describes binding proteins. In one or more embodiments, the binding protein may comprise any of the sequences of SEQ ID NO: 7 to SEQ ID NO: 30 (see Table 4). Each X in SEQ ID NO:7 to SEQ ID NO:30 can independently be any amino acid. In one or more embodiments, one or more of the Xs in a sequence can be A, C, D, G, N, S, T, or Y. In one or more embodiments, residue 17, residue 18, or both in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y. In one or more embodiments, one or more of the Xs in a sequence can be D, E, G, H, K, N, Q, R, or S. For example, in one or more embodiments, residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one more embodiments, residue 17 and residue 18 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y and residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one or more embodiments, one or more of the Xs in a sequence can be W. For example, in one or more embodiments, residue 43 of Con L1 (SEQ ID NO: 25), F L1 (SEQ ID NO: 26), G L1 (SEQ ID NO: 27), H L1 (SEQ ID NO: 28), I L1 (SEQ ID NO: 29), J L1 (SEQ ID NO: 30) is W. In one or more embodiments, the binding protein may comprise any of the sequences of SEQ ID NO:73 to SEQ ID NO:102 (see Table 9). In some embodiments, one or more of the Xs in a sequence can be G or S. For example, in one or more embodiments, the fourth residue (first X residue) in A L2 (SEQ ID NO: 98), B L2 (SEQ ID NO: 99), C L2 (SEQ ID NO: 100, D L2 (SEQ ID NO: 101), or E L2 (SEQ ID NO: 102) can be G or S. In one or more embodiments, the binding protein may comprise any of the sequences SEQ ID NO:111 to SEQ ID NO:145 (see Table 14). Each X can independently be any amino acid. In one or more embodiments, the binding protein comprises a sequence having at least 90% sequence identity to any of SEQ ID NO:31 to SEQ ID NO:53 (see Table 5), SEQ ID NO:103 to SEQ ID NO:106 (see Table 10), or SEQ ID NO:143 to SEQ ID NO:183. In another aspect, the present disclosure describes screening libraries. A screening library includes a plurality of screening proteins. Each screening protein of the plurality of screening proteins differs from a parental protein by at least one amino acid residue in the binding region. In one or more embodiments, each screening protein can comprise any of the sequences of SEQ ID NO: 7 to SEQ ID NO: 30 (see Table 4). Each X in SEQ ID NO:7 to SEQ ID NO:30 can independently be any amino acid. In one or more embodiments, one or more of the Xs in a sequence can be A, C, D, G, N, S, T, or Y. In one or more embodiments, residue 17, residue 18, or both in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y. In one or more embodiments, one or more of the Xs in a sequence can be D, E, G, H, K, N, Q, R, or S. For example, in one or more embodiments, residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one more embodiments, residue 17 and residue 18 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y and residue 21 in Con α2 (SEQ ID NO: 13), F α2 (SEQ ID NO: 14), G α2 (SEQ ID NO: 15), H α2 (SEQ ID NO: 16), I α2 (SEQ ID NO: 17), J α2 (SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one or more embodiments, one or more of the Xs in a sequence can be W. For example, in one or more embodiments, residue 43 of Con L1 (SEQ ID NO: 25), F L1 (SEQ ID NO: 26), G L1 (SEQ ID NO: 27), H L1 (SEQ ID NO: 28), I L1 (SEQ ID NO: 29), J L1 (SEQ ID NO: 30) is W. In one or more embodiments, each screening protein can include any of the sequences of SEQ ID NO:73 to SEQ ID NO:102 (see Table 9). In some embodiments, one or more of the Xs in a sequence can be G or S. For example, in one or more embodiments, the fourth residue (first X residue) in A L2 (SEQ ID NO: 98), B L2 (SEQ ID NO: 99), C L2 (SEQ ID NO: 100, D L2 (SEQ ID NO: 101), or E L2 (SEQ ID NO: 102) can be G or S. In one or more embodiments, each screening protein can include any of the sequences SEQ ID NO:111 to SEQ ID NO:145 (see Table 14). In another aspect, the present disclosure describes a screening method. The screening method includes forming a screening library. The method further includes exposing the screening library to a target. The method further includes sorting the screening library for screening proteins that bind to the target; and determining the amino acid sequence of at least one screening protein that bound to the target with a dissociation constant of one micromolar or less. BRIEF DESCRIPTION OF THE FIGURES The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. FIG.1. Overall synthetic ligand scaffold design. Design can be viewed as a three- dimensional factorial design with two topologies (β2αβ2and α3), each with five frameworks (different colors), and four or five paratope structures. Sites of paratope diversification are displayed as gray spheres. Sequences are detailed in FIG.2 and FIG. 3. FIG.2 and FIG.3. Synthetic scaffold sequence designs for the β2αβ2topology (FIG.2) and the α3topology (FIG.3) constructs. The following letters represent different degenerate codons used when designing each framework / paratope combination –X: NNK (all 20 amino acids); V: RGY (G, S); Y: DVY (A, C, D, G, N, S, T, Y); Z: VRN (D, E, G, H, K, N, Q, R, S). FIG.4 and FIG.5. Select synthetic scaffold designs exhibit high evolvability. The merged library of all 45 designs was sorted for specific binders to each indicated target. Deep sequencing of specific binding populations quantified enrichment of each design relative to the unsorted library. The resultant evolvability scores across all four binding targets are presented in descending order by median (shown as a black horizontal bar) for the α3topology (FIG.4) and for the β2αβ2topology (FIG.5). FIG.6, FIG.7, and FIG.8. Evolvability varies by topology, framework, and paratope. The median evolvability for binding to four distinct targets (FIG. 4 and FIG. 5) is shown for all combinations of framework and paratope (FIG.6); grouped by framework (FIG. 7); and grouped by paratope location (FIG.8). FIG.9, FIG.10, FIG.11, and FIG.12. Developability varies by topology, framework, and paratope. (FIG.9 and FIG.10) Yeast displaying ligand variants from each sublibrary were exposed to proteinase K at 37 ºC and sorted into eight tiers based on maintenance of full-length protein. Protease stability of libraries is shown across (FIG.9) frameworks (grouping paratopes) and (FIG.10) paratopes (grouping frameworks). Each box represents the performance of an individual combinatorial library after experiments run in triplicate. (*: p < 0.05 #: p < 0.01) (FIG. 11 and FIG.12) The merged libraries were evaluated for GFP expression across (FIG.11) frameworks and (FIG.12) paratopes. (*: p < 0.05 #: p < 0.01). (FIG. 13) The average developability scores for each library design is presented across all assays. FIG.14. Select scaffold designs exhibit high developability and evolvability while many others exhibit reduced performance. The median evolvability across four targets (FIG.4 and FIG. 5) is plotted versus the mean developability across four assays (FIG.9, FIG.10, FIG.11, FIG. 12, and FIG.13) for all 45 library designs. FIG.15 and FIG. 16. Amino acid preferences within scaffolds. (FIG.15) Residue frequency enrichment across each site within the α3J: α2scaffold across all eight assays. Strong red indicates a high enrichment, while a strong blue indicates strong depletion. Black box indicates wildtype residue. (FIG.16) The slope of amino acid frequency versus developability across all libraries is presented as a heatmap. Strong red colors represent a high positive slope while strong blues represent high negative slopes. FIG.17. Characterizing the recombinant yield and melting temperature of the top VEGF clones. (A) 24 selected VEGF binding clones reveal a distribution of moderate recombinant yield expression. (B) Distribution of melting temperatures for 16 clones calculated from circular dichroism experiments. FIG.18, FIG. 19, FIG.20, and FIG.21. Characterization of clone α3J:α2:6 reveals a well- folded, thermally stable, and strong VEGF binder. (FIG. 18) Circular dichroism spectra at 25 ºC (red) prior to raising the temperature to 95 ºC (black), then cooling back down to 25 ºC (blue). (FIG.19) Melting curve of α3J:α2:6 displaying the change in ellipticity (in millidegrees) as a function of temperature. (FIG.20) Affinity titration data to fit a binding curve to calculate the KD. 68% confidence interval shown in shaded blue. (FIG.21) Structural alignment of α3J framework (black) with the α3J:α2:6 clone (orange) predicted by α-fold2. Mutations away from the parental are shown as sticks. FIG.22. Constructed libraries match desired amino acid frequency. The amino acid frequencies across all merged libraries were determined via deep sequencing of ~9×105variants. FIG.23. Specific binders were enriched. The doubly-sorted populations of yeast- displayed ligands were sorted via magnetic beads for binding to control protein (IgG) or target protein. The number of yeast cells collected is shown. FIG.24. Scaffold topology affects the library evolvability performance for a particular target. Individual target scores were compared relative to its overall average across all campaigns. A score near 0 indicates the library scores across all campaigns are close to each other. FIG.25, FIG. 26, FIG.27, and FIG.28. Developability stratification. (FIG.25, FIG.26, and FIG.27) The merged library of scaffold variants was displayed on the surface of yeast, incubated with the indicated protease at 37 ºC or 55 ºC, washed, labeled with antibodies for the N- and C-terminal HA and V5 epitopes, and sorted into tiers via flow cytometry. (FIG 28) The merged library of scaffold variants was expressed as a genetic fusion to the 11th strand of GFP in E. coli co-expressing the remainder of GFP. Cells were sorted via flow cytometry based on GFP signal. FIG.29, FIG. 30, FIG.31, and FIG.32. Framework and paratope designs affect protease stability. Yeast displaying ligand variants from each sublibrary were exposed to proteinase K (FIG.29 and FIG.30) and thermolysin (FIG. 31 and FIG.32) at 55 ºC and sorted into eight tiers based on maintenance of full-length protein. Deep sequencing of resultant tiers yields a developability score for each sublibrary, which were evaluated across (FIG.29 and FIG.31) frameworks (grouping paratopes) and (FIG.30 and FIG. 32) paratopes (grouping frameworks). Each box represents the performance of an individual combinatorial library after experiments run in triplicate. (*: p < 0.05 #: p < 0.01) FIG.33 and FIG.34. Stability correlations. (FIG. 33) Proteinase K stability correlates across temperatures, with higher thermal stability in α3topologies. The protease stabilities of each sublibrary are compared at 37 ºC and 55 ºC. A linear correlation is evaluated for the β2αβ2and α3topologies. (FIG. 34) Proteinase K stability moderately correlates with thermolysin stability across libraries. FIG.35. Site-wise amino acid enrichment reveals some motifs that affect scaffold developability and evolvability. Residue frequency enrichment across each site within the scaffold paratope across all eight assays. Strong red indicates a high enrichment, while a strong blue indicates a strong depletion. Black box indicates wildtype residue. FIG.36. Amino acid effect on evolvability. The slope of amino acid frequency versus evolvability across all libraries is presented as a heatmap. Strong red colors represent a high positive slope while strong blues represent high negative slopes. FIG.37. Top clones originate from three libraries. Blue indicates mutations within the initial paratope design while red are mutations due to error prone PCR. Naming convention is as follows – <framework>: <paratope>: <clone number>. FIG.38, FIG. 39, FIG.40, and FIG 41. Secondary structure analysis. Purified protein was evaluated by circular dichroism to measure ellipticity as a function of wavelength at 25 ºC (red), 95 ºC (black), and 25 ºC after heating (blue). FIG.42, FIG. 43, FIG.44, and FIG.45. Thermal stability analysis. Purified protein was evaluated by circular dichroism to measure the ellipticity at 218 nm as temperature was increased from 20 ºC to 95 ºC by 3 ºC per minute. FIG.46, FIG. 47, and FIG.48. Clone characterization of β2αβ2D:β1-4:1 (FIG. 46), α3J:α2:7 (FIG.47), and α3J:α2:14 (FIG. 48) reveals well-folded, thermally stable, and strong VEGF binders. Circular dichroism spectra at 25 ºC (red) prior to raising the temperature to 95 ºC (black), then cooling back down to 25 ºC (blue)(left). Melting curve displaying the change in ellipticity (in millidegrees) as a function of temperature (left middle). Affinity titration data to fit a binding curve to calculate the KD (right middle).68% confidence interval shown in shaded blue. Structural alignment of parental framework (black) with the variant predicted by alphafold2. Mutations away from the parental are shown as spheres (right). FIG.49 and FIG. 50. AlphaFold2 structures suggest clones retain their original topological structure. RMSD values from structural alignment for each variant with its respective parental framework is presented. *: The majority of the pLDDT values for the α3J:α2:16 model were < 70, therefore the model was omitted from analysis. Cartoon structures from two clones with the highest RMSD values are shown in tan aligned with their parental in black. Mutations within the α2design are displayed as sticks in blue, while mutations due to epPCR are shown in red. α3J:α2:2 has two notable mutations, S17C & D18C, in proximity potentially creating a di- sulfide bond contributing to its high RMSD. Clone α3J:α2:11 contains an R27P mutation at the end of the α2helix. FIG.51. Structural alignments of all clones with its respective parental framework are superimposed on each other. FIG.52. A schematic depiction of the tertiary structure of the binding proteins consistent with embodiments of the present disclosure. Modified from Protein Data Bank No.5UOI. FIG.53. A schematic depiction of the secondary structures of the binding proteins consistent with embodiments of the present disclosure. FIG.54. A schematic depiction of the tertiary structure of the binding proteins consistent with embodiments of the present disclosure. Modified from Protein Data Bank No.5UP51. FIG.55. A schematic depiction of the secondary structures of the binding proteins consistent with embodiments of the present disclosure. FIG.56. Four highly stable frameworks (FW1, FW2, FW3, and FW4) were diversified at three different paratope secondary structures (Loops, Helix, and Sheets (also called strands)). Within the sheets (strands), the number and location of diversified sites was varied. Structure of frameworks and library design with framework stabilities. FIG.57. Sequence of frameworks and library designs of FIG.56. • indicates that the amino acid of the parental sequence was maintained. X indicates amino acid diversity. FIG.58. Structural similarities between the library designs of FIG.56. FIG.59. Yeast displaying the indicated βαββ variant were incubated with titrated concentrations of B7-H3 or PSMA. Binding was detected via flow cytometry and normalized to the range between the fitted maximum and minimum values. Additional curves in FIG.83 and FIG. 84. The squares, triangles and crosses represent different replicates. FIG.60. Yeast displaying the indicated βαββ variant were incubated with 100 nM non- target proteins or 50 nM target proteins, and binding was assessed via flow cytometry. The figure shown is one representative trial; additional trials and the remaining binders are shown in FIG. 85 and FIG.86. FIG.61. Purified βαββ, variant B7-H3 #1, was evaluated via circular dichroism as a wavelength scan from 190 – 260 nm at 25 °C (before or after 95 °C incubation) or 95 °C as well as a temperature scan from 27 °C to 95 °C with monitoring at 218 nm. Additional spectra are shown in FIG.87, FIG.88, FIG.89, and FIG.90. FIG.62. Affinities, average maximum off-target binding (as percentage of target binding), Tmmeasured via CD, structural deviation from wild-type (RMSD via AlphaFold2), AlphaFold2 confidences (Ave. pLDDT), and bacterial expression levels. N.D. indicates that a Tmwas unable to be calculated. B7-H3 #4 had too low a yield to measure CD. PSMA #1 and IgG #3 had uncharacteristic CD curves and thus Tms were unable to be calculated. FIG.63. AlphaFold2 predictions of structures are overlaid on top of each parent structure (black).22 proteins emerged from FW1, 22 from FW2, 3 from FW3, and 13 from FW4. FIG. 64. Histogram of structural deviation between predicted protein structure versus the parent excluding two proteins with an average AlphaFold2 pLDDT < 70. FIG.65. The evolvability scores (enrichment of that library design in the binder pool relative to the unsorted pool) are shown for each framework across all paratope designs. Significance bars colors correspond to framework. FIG.66. The evolvability scores (enrichment of that library design in the binder pool relative to the unsorted pool) are shown for each paratope type across all paratope sizes and locations in each framework. Significance bars colors correspond to framework. FIG.67. Evolvability scores for each paratope structure, computed as the median across frameworks and particular sets of paratope sites, are plotted for each target. FIG.68. Comparison of developability scores by framework. Developability scores computed as the enrichment of variants in the top 5% of protease resistant cells or top 10% of GFP expressing cells, normalized to the median across libraries are shown for proteinase K, thermolysin, and split GFP. Statistical significance is shown under graphs with matching colors and line thickness; significance is designated by solid or dotted lines. FIG.69. Comparison of developability scores by paratope. Developability scores computed as described in FIG.68. Statistical significance is shown under graphs with matching colors and line thickness; significance is designated by solid or dotted lines. FIG.70. Comparison of developability scores by sheet diversification. Developability scores computed as described in FIG.68. Statistical significance is shown under graphs with matching colors and line thickness; significance is designated by solid or dotted lines. FIG.71. The average stability scores (enrichment upon protease resistance sorting) after exposure to proteinase K for the populations evolved to bind target are plotted versus the average stability scores of the naïve library. FW3 proline (pink, small shapes) have very few binders that were measured for stability. Dotted line indicates equal stabilities between the binders and the naïve library. FIG.72. The average stability scores (enrichment upon protease resistance sorting) after exposure to thermolysin for the populations evolved to bind target are plotted versus the average stability scores of the naïve library. FW3 proline (pink, small shapes) have very few binders that were measured for stability. Dotted line indicates equal stabilities between the binders and the naïve library. FIG.73. Nine designs are mutually developable and evolvable, with three especially performant designs. The median evolvability score is plotted versus mean developability score. Developability scores above one indicate that the library is more developable than the median library, while evolvability scores above one indicate that the library is more enriched in the binder pool than the naïve library. Paratope is indicated by shape, while framework is indicated by color. FIG.74. Evolvability scores for each target for the nine most developable / evolvable libraries. FIG.75. Developability scores for each target for the nine most developable / evolvable libraries. FIG.76. Sitewise amino acid enrichments in binding and developable variants from the sheets libraries. Enrichment values compare the frequency of each amino acid in the binder pool to the frequency in the unsorted library for each of the four frameworks. Proteinase K (at 37 °C and 55 °C), thermolysin (at 55 °C and 75 °C), and split GFP are shown. Values consist of the average for sheets across all four frameworks, so wildtype is not indicated. FIG.77. Sitewise amino acid enrichments in binding and developable variants from the sheets libraries. Enrichment values compare the frequency of each amino acid in the most developable pool to the frequency in the unsorted library. Proteinase K (at 37 °C and 55 °C), thermolysin (at 55 °C and 75 °C), and split GFP are shown. Values consist of the average for sheets across all four frameworks, so wildtype is not indicated. FIG.78A-78D. DNA sequences for library design for FW1 (FIG.78A), FW2 (FIG.78B), FW3 (FIG.78C), and FW4 (FIG78D). DNA sequences were designed to match the intended amino acids and diversity detailed in FIG.57. Red sites indicate a diversified region. At several sites, mutation stability data (from 41) indicates that P is very destabilizing. At any site where the consensus stability score measured for proline was more than 17% below the wild-type, P was excluded from the diversity. To remove P, cytosine could be removed as a possibility from the first or second nucleotide site, which would also remove either Q and H or A and T, respectively. If one of those amino acids was the wildtype for that site for any of the four proteins, the other two amino acids were removed from that site. If a different amino acid was wildtype, the two amino acids that were shown to have a lower average stability consensus score when added from the stability data for protein FW1 were removed for all four proteins. For example, at site 29 on protein FW1, the stability data indicated addition of P resulted in a stability score of 3.91, which motivates exclusion of proline; to retain wild-type T, a DNK was used to exclude P, H, and Q. At site 14, the stability data indicated addition of a proline resulted in a stability score of 4.18, which motivates exclusion of P; H and Q have stabilities of 6.1 and 5.61, whereas A and T yield stabilities of 5.59 and 5.42; thus, an NDK codon is used to exclude P, A, and T. FIG.79. Comparison of average amino acid frequencies between design and experimental result. Percent difference is actual percentage of an amino acid that appears in the library minus the designed percentage. The average presented in the main text is the mean of the absolute values of all percent differences. FIG.80. Sequences of characterized clones are shown with additional residues appended during production indicated in red. The library of origin for each clone are shown. The percentages of secondary structure are computed from CD data using Bestsel for structure prediction. B7-H3 #4 was not produced with a high enough yield to measure structure via CD. FIG.81. PDB structures of protein targets. The PDB code is listed beneath the name of each target. The study uses human B7-H3, however, no experimental structure for human B7-H3 was available so murine B7-H3 is shown. The study also uses insulin receptor isoform A, however, no experimental structure for IRA was available, so insulin receptor is shown. FIG.82. Enrichment of specific binders from βαββ libraries. Yeast displaying populations of βαββ variants enriched for binding to B7-H3, CD22, IgG, PSMA, Tem8, NKp46 and IRA were incubated with the indicated concentration of B7-H3, CD22, IgG, PSMA, Tem8, NKp46 or IRA, and binding was assessed via flow cytometry. FIG.83 and FIG.84. Tested clones exhibit high affinity and specificity. Yeast displaying βαββ variants were incubated with titrated concentrations of target, and binding was assessed via flow cytometry. Affinities were calculated as the average KDof each trial via minimization of squared error of a 1:1 binding model. The squares, triangles and crosses represent different replicates. FIG.85 and FIG.86. Tested clones exhibit high affinity and specificity. Yeast displaying the indicated βαββ variant were incubated with 50 nM target or 100 nM off-target, and binding was assessed via flow cytometry with subtraction of background fluorescence. FIG.87, FIG.88, FIG.89, and FIG.90. Most βαββ proteins are very stable and have elements of the correct secondary structure. Purified βαββ was evaluated via circular dichroism using a wavelength scan from 190 nm to 260 nm at 25 °C (before or after 95 °C incubation) or 95 °C as well as a temperature scan from 25 °C to 95 °C with monitoring at 218 nm. B7-H3 #4 lacked sufficient protein to measure CD, so it is not included on this figure. FIG.91. The evolvability scores (enrichment of that library design in the binder pool relative to the unsorted pool) are shown for each target, paratope type (helix, loops, two-sheet (two-strand), and three-sheet (three-strand) libraries), and framework. FIG.92. Individual target and median evolvability scores (enrichment of that library design in the binder pool relative to the unsorted pool) are shown for the sheet libraries created from each framework. FIG.93. For each individual library, scores are calculated based upon the fraction of each library found in the highest gate relative to the fraction of the library found in the unsorted pool, denoted stability score. An alternative method calculates a score based upon the enrichment of that library considering all the gates, denoted stability enrichment score. Method 1 vs method 2 for proteinase K. FIG.94. Method 1 vs Method 2 for thermolysin calculated according to FIG.93. FIG.95. Amino acid enrichment values for FW1 β ABC8 shown as 1-β ABC8. Scores indicate the enrichment or depletion of an amino acid relative to its frequency in the naïve or unsorted library. Proteinase K and thermolysin indicate the average of the two temperatures measured. FIG.96. Amino acid enrichment values for FW1 α shown as 1- α. Scores indicate the enrichment or depletion of an amino acid relative to its frequency in the naïve or unsorted library. Proteinase K and thermolysin indicate the average of the two temperatures measured. FIG.97. A schematic depiction of the tertiary structure of the binding proteins consistent with embodiments of the present disclosure. Modified from Protein Data Bank No.5UP5. FIG.98. A schematic depiction of the secondary structures of the binding proteins consistent with embodiments of the present disclosure. FIG.99. IRA binding protein data. Data shown are an average z score. Binding was measured to IRA and IRB at multiple concentrations (5 nM,50 nM, 100 nM, and 500 nM) and the fluorescent signal had background removed, then was normalized by the levels of IRA / IRB. The x axis is the average of z scores (of A binding signal) calculated for each of those concentrations. The y axis is average z signal of a normalized signal divided by the b signal. FIG.100 and FIG.101. Secondary structure analysis. Purified protein was evaluated by circular dichroism to measure ellipticity as a function of wavelength at 25 °C (red), 95 °C (black), and 25 °C after heating (blue). FIG.102 and FIG.103. Thermal stability analysis. Purified protein was evaluated by circular dichroism to measure the ellipticity at 218 nm as the temperature was increased from 20 °C to 90 °C (black) by 3 °C per minute. The fraction folded as a function of temperature is displayed for all clones. FIG.104. Clone characterization of β2β2D:β1-4:1(top), a3J:a2:7 (middle), and a3J:a2:13 (bottom) reveals well-folded, thermally stable, and strong VEGF binders. Circular dichroism spectra at 25 °C (red) prior to raising the temperature to 95 °C (black) , then cooling ack down to 25 °C (blue). Melting curve displaying the change in ellipticity as a function of temperature. Affinity titration data to fit a binding curve to calculate the KD(68% confidence interval shown in shaded blue). Structural alignment of parental framework (black) with variant predicted by alphafold 2. Mutations away from the parental framework as shown as spheres. FIG.106, FIG.107, and FIG. 108. Tested B7-H3 variants exhibit high specificity to genuine cell-expressed target. Recombinantly produced B7-H3 binding variants were incubated with B7-H3 expressing MS1 cells or HEK293 B7-H3 KO cells, and binding was assessed via flow cytometry. B7-H3 #4 was not assessed due to very low recombinant yields. Target positive cells were treated at 50 nM of the B7-H3 binding variants, while KO cells were treated at 1000 nM. Data is provided as the florescence with the background mammalian cell florescence removed. FIG.106 shows replicate 1. FIG.107 shows replicate 2. FIG.108 shows replicate 3. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS This disclosure describes binding proteins, screening proteins, screening libraries that include at least one binding protein and / or at least one screening protein, methods of screening such libraries, binding compounds that include at least one of the binding proteins (binding compounds), and methods of using such binding compounds. As used herein, the term “binding protein” refers to a protein that is an anti-target protein that binds to a target with a dissociation constant (Kdor KD) of 1 micromolar or less. Exemplary platforms in which binding proteins or binding compounds may be used include, but are not limited to, chimeric antigen receptor therapies (e.g., CAR-NK therapy, CAR-T therapy, CAR-macrophage therapy, etc.), multispecific immune cell engager technologies (e.g., bispecific killer engagers, trispecific killer engagers, bispecific T cell engagers, trispecific T cell engagers, etc.), targeted immunotherapies (e.g., targeted ADAM17 blocker (TAB) therapy), delivery of therapeutics (e.g., antibody-drug conjugates, delivery of therapeutic radioisotopes, delivery of toxins, delivery of cytokines, delivery of chemokines), imaging technologies (delivery of labeling constructs and / or labeling radioisotopes), or cell and / or ligand capture technologies (e.g., ELISA, etc.). ^ Binding proteins empower biology, medicine, molecular therapeutics, and diagnostics. Small, single-domain protein scaffolds have many promising properties due to their small size. For example, single-domain protein scaffolds can exhibit high tumor penetration. Additionally, single-domain protein scaffolds may have high modularity which enables linkage to other proteins for multifunctional fusions and bispecifics. Their simple structure and lack of need for glycosylation allows for production in bacteria or chemical synthesis, resulting in easy manufacturing. Small size also allows for controlled clearance kinetics. For example, small proteins are effective for early time molecular imaging due to fast clearance resulting in high contrast, yet clearance times can be extended via addition of poly(ethylene glycol), Fc, or an albumin-binding peptide as needed. Engineered binding proteins empower biotechnologies in industrial, medical, and agricultural settings. Specifically, molecular recognition binding proteins are being used and explored for targeted therapy and diagnostic applications. A common approach to engineer high- affinity, specific binding proteins entails scaffold proteins. Scaffold proteins include a conserved framework to provide structural integrity for stability and reduced entropic cost of binding. Additionally, scaffold proteins include a variable region (binding region; also called the active site), that is engineered to provide new binding functions, a property called evolvability or innovability. The scaffold concept aims to decouple the functional binding site from the stabilizing core. These scaffolds are typically designed based upon a highly stable starting protein due to their ability to tolerate more destabilizing, but functional, mutations on the path to discovery of new function. Many small protein scaffolds are in use, including affibodies, fibronectins, anticalins, cystine knots, Gp2, knottins, and DARPins and many others. Several of these small proteins have reached clinical trials, and a few have been FDA approved. These scaffolds have a wide variety of topologies with varied binding paratope structures (binding site structures), including loops (both flexible and constrained), α helices and β strands. Yet, the evolvability and developability of these scaffolds vary significantly, which renders the ideal scaffold uncertain. Maintaining developability is non-trivial because introducing new functions requires varying an appreciable fraction of these small domains. Yet, decoupling the engineered paratope from the framework, a beneficial approach to evolvability, is challenged in small domains. Small scaffold proteins exhibit a range of performance across metrics including evolvability and developability. Developability is the set of properties a protein often possesses to be translated from the laboratory to genuine use, such as stability, solubility, and cellular expression. Developability liabilities add substantial cost and time to drug discovery, reduce efficacy, and may prevent utility altogether. Evolvability is the efficiency of discovery of new function from a naïve library. Mutations that change protein function are generally destabilizing, resulting in a trade-off between developability and evolvability. To complicate matters further, proteins often do not come with ideal properties because they evolved to fit environmental pressures rather than for our specific needs. Despite extensive engineering of scaffold proteins across various topologies, the factors that dictate performance remain incompletely understood, thereby motivating fundamental elucidation of the effects of protein topology, parental framework sequence, paratope structure (binding region structure), and paratope sequence (binding region sequence) on scaffold developability and evolvability. Moreover, current scaffolds all present various liabilities, inspiring identification of ligand scaffolds with an improved balance of evolvability and developability. Despite a wide array of protein scaffolds having been engineered for binding, the biophysical elements that drive developability and evolvability are not fully understood. In particular, engineering novel function while maintaining biophysical integrity within the context of small, single-domain proteins is challenged by the integrated nature of the structural framework and the evolved binding site. Nature’s primary example of evolvable binding proteins, the antibody, is the dominant scaffold for clinical and biotechnological applications. The structure of antibodies can be less than optimal for certain therapeutic, clinical, or basic research functions. For example, the large size of antibodies can inhibit effective tissue penetration, which can decrease therapeutic efficacy. As another example, the multi-domain structure of antibodies can hinder modularity for multifunctional applications. As yet another example, the variable developability of antibodies can hinder utility. As protein size is reduced, separation of framework and paratope is increasingly challenging. This heightens the need for paratope efficiency to provide sufficient surface area to achieve specific, high-affinity interaction with a target while limiting destabilizing diversification. Effective identification of tolerant paratope sites, and amino acid options, can aid evolutionary efficiency. More fundamentally, the molecular factors that influence the efficacy of a protein topology and paratope design to serve as a scaffold are not well understood. Binding Proteins The present disclosure describes, in one aspect, binding proteins. Binding proteins are able to bind to one or more targets. Binding proteins can be derived from a variety of parental sequences that include a variety of secondary and tertiary structures and topologies. As used herein, the term “secondary structure” refers to the local confirmation of the protein backbone defined by the hydrogen bonding pattern between the carbonyls and the amide hydrogens of the protein backbone in that location. Examples of secondary structures include alpha-helices, beta-sheets, and loops. As used herein, the terms “alpha-helix,” “α-helix,” “helix,” “a-helix,” and “α” are used interchangeably to refer to a right handed helix conformation where the amide hydrogen of the backbone of at least three consecutive residues hydrogen bonds with the carbonyl of a residue that is three (310helix; an average of 3 residues per turn, 10 atom member ring), four (3.613helix; an average of 3.6 residues per ring, 13 atom member ring), or five residues (π-helix) earlier in the sequence. In one or more embodiments, the alpha-helices of the present disclosure are 3.613helices. As used herein, the terms “beta-sheet,” “β-sheet,” and “b-sheet” are used interchangeably to refer to at least two adjacent beta-strands that interact by hydrogen bonding between at least a portion of the carbonyls and N-H groups of a first beta-strand with at least a portion of the carbonyls and N-H groups of at least one adjacent second beta-strand. Beta-sheets can be antiparallel or parallel. The terms “beta-strand,” “β-strand,” “b-strand,” and “β” are used interchangeably to refer to a sequence of consecutive amino acids that are a part of a beta-sheet. As used herein, the term “loop” refers to an unordered portion of a protein that couples two secondary structures (e.g., two beta-strands, two alpha-helices, or a beta-strand and an alpha- helix). As used herein, the term “tertiary structure” refers to the three-dimensional shape of a protein formed by the folding of the secondary structures of the protein. The tertiary structure can be partially described by the topology of the protein—i.e., the order of the secondary structures or components of secondary structures from the N-terminus to the C-terminus. A full description of tertiary structure can include the precise locations of the atoms in three- dimensional space. In one or more embodiments, the binding proteins include or are derived from a parental sequence that includes three α-helix secondary structure motifs that fold into a tertiary structure having an N-terminus to C-terminus ααα (also called α3, α3, A3, A3 a3, a3, AAA and aaa) topology where each α is an alpha-helix. In one or more embodiments, the binding proteins include or are derived from a parental sequence that includes three α-helix secondary structure motifs that fold into a tertiary structure having an N-terminus to C-terminus ββαββ (also called BBABB, bbabb) topology where α is an alpha-helix and β is a beta-strand. In in or more embodiments, the binding proteins include or are derived from a parental sequence that includes three α-helix secondary structure motifs that fold into a tertiary structure having an N-terminus to C-terminus βαββ (also called BABB, babb, and EHEE). The binding proteins include a parental amino acid sequence that has regions of variability (i.e., binding regions as discussed herein) where the regions of variability can be engineered to bind to a specific target. The binding proteins of the present disclosure can be derived from a variety of parental protein (also called framework sequences, frameworks, scaffolds, scaffold sequences, and framework structures). A binding protein derived from a parental protein is a protein that includes the parental protein sequence except at one or more binding region residues (as described herein). As such, the binding proteins of the present disclosure can be described as derived from a parental sequence. For example, a binding protein may be derived from a parental sequence by varying one or more amino acids in the binding region. In one or more embodiments, the binding protein derived from a parental protein may deviate from the secondary structure or tertiary structure of the parental protein. For example, a binding protein derived from a parental protein may have a beta-sheet that includes only two beta-strands whereas the beta-sheet of the parental protein has three beta-strands. It is understood that the features of the binding proteins described herein are features of the parental protein from which it is derived. The present disclosure includes binding proteins that have a variety of percent “identity” and / or a percent “similarity” to the binding proteins disclosed herein. As used herein, a protein is “structurally similar” to a reference protein (e.g., parental protein) if the amino acid sequence of the protein possesses a specified amount of identity compared to the reference protein. Structural similarity of two proteins can be determined by aligning the residues of the two proteins (for example, a candidate protein and the reference protein) to optimize the number of identical amino acids along the lengths of their sequences; gaps in either or both sequences are permitted in making the alignment in order to optimize the number of identical amino acids, although the amino acids in each sequence must nonetheless remain in their proper order. A candidate protein is the protein being compared to the reference protein. A candidate protein can be isolated, for example, from an animal, or can be produced using recombinant techniques, or chemically or enzymatically synthesized. A pair-wise comparison analysis of amino acid sequences can be carried out using the BESTFIT algorithm in the GCG package (version 10.2, Madison WI). Alternatively, proteins may be compared using the Blastp program of the BLAST 2 search algorithm, as described by Tatiana et al., (FEMS Microbiol Lett, 174, 247-250 (1999)), and available on the National Center for Biotechnology Information (NCBI) website. The default values for all BLAST 2 search parameters may be used, including matrix = BLOSUM62; open gap penalty = 11, extension gap penalty = 1, gap x_dropoff = 50, expect = 10, wordsize = 3, and filter on. In the comparison of two amino acid sequences, structural similarity may be referred to by percent “identity” or may be referred to by percent “similarity.” “Identity” refers to the presence of identical amino acids. “Similarity” refers to the presence of not only identical amino acids but also the presence of conservative substitutions. A conservative substitution for an amino acid in a protein may be selected from other members of the class to which the amino acid belongs. For example, it is well-known in the art of protein biochemistry that an amino acid belonging to a grouping of amino acids having a particular size or characteristic (such as charge, hydrophobicity, and hydrophilicity) can be substituted for another amino acid without altering the activity of a protein, particularly in regions of the protein that are not directly associated with biological activity. For example, nonpolar (hydrophobic) amino acids include alanine, leucine, isoleucine, valine, proline, phenylalanine, tryptophan, and tyrosine. Polar neutral amino acids include glycine, serine, threonine, cysteine, tyrosine, asparagine, or glutamine. The positively charged (basic) amino acids include arginine, lysine, or histidine. The negatively charged (acidic) amino acids include aspartic acid or glutamic acid. Conservative substitutions include, for example, Lys for Arg or vice versa to maintain a positive charge; Glu for Asp or vice versa to maintain a negative charge; Ser for Thr or vice versa so that a free -OH is maintained; or Gln for Asn or vice versa to maintain a free -NH2. Likewise, biologically active analogs of a proteins containing deletions or additions of one or more contiguous or noncontiguous amino acids that do not eliminate a functional activity of the protein are also contemplated. The binding protein may be 30 amino acids or longer, 35 amino acids or longer, 36 amino acids or longer, 38 amino acids or longer, 39 amino acids or longer, 40 amino acids or longer, 41 amino acids or longer, 42 amino acids or longer, 43 amino acids or longer, 44 amino acids or longer, 45 amino acids or longer, 46 amino acids or longer, 50 amino acids or longer, or 55 amino acids or longer. The binding protein may be 60 amino acids or shorter, 55 amino acids or shorter, 50 amino acids or shorter, 46 amino acids or shorter, 45 amino acids or shorter, 44 amino acids or shorter, 43 amino acids or shorter, 42 amino acids or shorter, 41 amino acids or shorter, 40 amino acids or shorter, 39 amino acids or shorter, 38 amino acids or shorter, 36 amino acids or shorter, or 35 amino acids or shorter. In one or more embodiments, the binding protein is 30 to 60, 30 to 55, 30 to 50, 30 to 46, 30 to 45, 30 to 44, 30 to 44, 30 to 43, 30 to 42, 30 to 41, 30 to 40, 30 to 39, 30 to 38, 30 to 36, 36 to 60, 36 to 55, 36 to 50, 36 to 46, 36 to 45, 36 to 44, 36 to 44, 36 to 43, 36 to 42, 36 to 41, 36 to 40, 36 to 39, 36 to 38, 38 to 60, 38 to 55, 38 to 50, 38 to 46, 38 to 45, 38 to 44, 38 to 43, 38 to 42, 38 to 41, 38 to 40, 38 to 39, 39 to 60, 39 to 55, 39 to 50, 39 to 46, 39 to 45, 39 to 44, 39 to 44, 39 to 43, 39 to 42, 39 to 41, 39 to 40, 40 to 60, 40 to 55, 40 to 50, 40 to 46, 40 to 45, 40 to 44, 40 to 44, 40 to 43, 40 to 42, 40 to 41, 41 to 60, 41 to 55, 41 to 50, 41 to 46, 41 to 45, 41 to 44, 41 to 43, 41 to 42, 42 to 60, 42 to 55, 42 to 50, 42 to 46, 42 to 45, 42 to 44, 42 to 43, 43 to 60, 43 to 55, 43 to 50, 43 to 46, 43 to 45, 43 to 44, 44 to 60, 44 to 55, 44 to 50, 44 to 46, 44 to 45, 45 to 60, 45 to 55, 45 to 50, 45 to 46, 46 to 60, 46 to 55, 46 to 50, 50 to 60, 50 to 55, or 55 to 60 amino acids in length. Binding proteins derived from proteins having a three-helix bundle In one or more embodiments, the binding protein is or is derived from a protein having an α3tertiary structure. FIG. 52 depicts the α3tertiary structure of a binding protein 1. The binding protein 1 includes an N-terminal portion 5, a first alpha-helix 20, a first loop 30, a second alpha- helix 50, a second loop 40, a third alpha-helix 60, and a C-terminal portion 7. FIG.53 depicts the secondary structure and secondary structural components (e.g., alpha-helices) of the binding protein 1 that fold into the tertiary structure of FIG.52. The first alpha-helix 20 is coupled to the second alpha-helix 50 through the first loop 30. The second alpha-helix 50 is coupled to the third alpha-helix 60 through the second loop 40. A binding protein of the present disclosure may be of any suitable length. The length of the binding protein is the number of consecutive amino acid residues that form the α3topology described herein. For example, in embodiments, where a binding protein is coupled to a second proteinaceous component and / or includes additional sequences on the C-terminal or N-terminal end (e.g., for purification purposes), the additional amino acids are not included in the length of the binding protein. The binding protein may be 30 amino acids or longer, 35 amino acids or longer, 36 amino acids or longer, 38 amino acids or longer, 39 amino acids or longer, 40 amino acids or longer, 41 amino acids or longer, 42 amino acids or longer, 43 amino acids or longer, 44 amino acids or longer, 45 amino acids or longer, 46 amino acids or longer, 50 amino acids or longer, or 55 amino acids or longer. The binding protein may be 60 amino acids or shorter, 55 amino acids or shorter, 50 amino acids or shorter, 46 amino acids or shorter, 45 amino acids or shorter, 44 amino acids or shorter, 43 amino acids or shorter, 42 amino acids or shorter, 41 amino acids or shorter, 40 amino acids or shorter, 39 amino acids or shorter, 38 amino acids or shorter, 36 amino acids or shorter, or 35 amino acids or shorter. In one or more embodiments, the binding protein is 30 to 60, 30 to 55, 30 to 50, 30 to 46, 30 to 45, 30 to 44, 30 to 44, 30 to 43, 30 to 42, 30 to 41, 30 to 40, 30 to 39, 30 to 38, 30 to 36, 36 to 60, 36 to 55, 36 to 50, 36 to 46, 36 to 45, 36 to 44, 36 to 44, 36 to 43, 36 to 42, 36 to 41, 36 to 40, 36 to 39, 36 to 38, 38 to 60, 38 to 55, 38 to 50, 38 to 46, 38 to 45, 38 to 44, 38 to 43, 38 to 42, 38 to 41, 38 to 40, 38 to 39, 39 to 60, 39 to 55, 39 to 50, 39 to 46, 39 to 45, 39 to 44, 39 to 44, 39 to 43, 39 to 42, 39 to 41, 39 to 40, 40 to 60, 40 to 55, 40 to 50, 40 to 46, 40 to 45, 40 to 44, 40 to 44, 40 to 43, 40 to 42, 40 to 41, 41 to 60, 41 to 55, 41 to 50, 41 to 46, 41 to 45, 41 to 44, 41 to 43, 41 to 42, 42 to 60, 42 to 55, 42 to 50, 42 to 46, 42 to 45, 42 to 44, 42 to 43, 43 to 60, 43 to 55, 43 to 50, 43 to 46, 43 to 45, 43 to 44, 44 to 60, 44 to 55, 44 to 50, 44 to 46, 44 to 45, 45 to 60, 45 to 55, 45 to 50, 45 to 46, 46 to 60, 46 to 55, 46 to 50, 50 to 60, 50 to 55, or 55 to 60 amino acids in length. The binding proteins of the present disclosure include an N-terminal portion (5). The N- terminal portion defines the N-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the N-terminus of the binding compound may not be the N-terminus of the binding protein. In one or more embodiments, the N-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the N-terminal portion includes one residue that is not a part of a secondary structure. The ability of the N-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids in that portion. The first alpha-helix (1H; 20) includes a first helix N-terminus (1H-N; 21) and a first helix C-terminus (1H-C; 22). The 1H-N is the most N-terminal amino acid residue of the first alpha-helix. The 1H-C is the most C-terminal amino acid residue of the first alpha-helix. In one or more embodiments, the first alpha-helix includes 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acids residues. In one or more embodiments, the first alpha-helix includes 20 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, or 4 or fewer amino acid residues. In one or more embodiments, the first alpha-helix includes 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. The second alpha-helix (2H; 50) includes a second helix N-terminus (2H-N; 51) and a second helix C-terminus (2H-C; 52). The 2H-N is the most N-terminal amino acid residue of the second alpha-helix. The 2H-C is the most C-terminal amino acid residue of the second alpha- helix. In one or more embodiments, the second alpha-helix includes 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acids residues. In one or more embodiments, the second alpha-helix includes 20 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the second alpha-helix includes 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. The third alpha-helix (3H; 60) includes a third helix N-terminus (3H-N; 61) and a third helix C-terminus (3H-C; 62). The 3H-N is the most N-terminal amino acid residue of the third alpha-helix. The 3H-C is the most C-terminal amino acid residue of the third alpha-helix. In one or more embodiments, the third alpha-helix includes 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acids residues. In one or more embodiments, the third alpha-helix includes 20 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the third alpha- helix includes 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. The first loop (1L; 30) couples the first alpha-helix (20) to the second alpha-helix (50). The first loop includes a first loop N-terminus (1L-N; 31) and a first loop C-terminus (1L-C; 32). The 1L-N is the most N-terminal amino acid residue of the first loop. The 1L-C is the most C- terminal amino acid residue of the first loop. The 1L-N of the first loop is coupled to the 1H-C of the alpha-helix and the 1L-C is coupled to the 2H-N of the second alpha-helix. In one or more embodiments, the first loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the first loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the first loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The second loop (2L; 40) couples the second alpha-helix (50) to the third alpha-helix (60). The second loop includes a second loop N-terminus (2L-N; 41) and a second loop C- terminus (2L-C; 42). The 2L-N is the most N-terminal amino acid residue of the second loop. The 2L-C is the most C-terminal amino acid residue of the second loop. The 2L-N of the first loop is coupled to the 2H-C of the second alpha-helix and the 2L-C is coupled to the 3H-N of the third alpha-helix. In one or more embodiments, the second loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the second loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the second loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The C-terminal portion (7) defines the C-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the C-terminus of the binding compound may not be the C-terminus of the binding protein. In one or more embodiments, the C-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the C-terminal portion includes one amino acid that is not a part of a secondary structure. The ability of the C-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids. In one or more embodiments, the 4B-C of the fourth beta-strand defines the C-terminus. Specific amino acid residue locations within the first alpha-helix, the second alpha-helix, the third alpha-helix, the first loop, and the second loop can be denoted by counting the amino acid residues from the N-terminal or C-terminal amino acid residue of a specified motif (e.g., the 1L-C, 2H-N, and so on). When counting residue numbers from the N-terminal amino acid residue of a specified motif, the residue may be identified as x-N(1+y) where x identifies the motif (1H, 2H, 3H, 1L, or 2L) and y is the residue number counting from x-N where the residue number of x-N is 1. For example, 1H-N(2) is the second amino acid residue in the first alpha- helix. When counting residue numbers from the C-terminal amino acid residue of a specified motif, the residue may be identified as x-C(-1-y) where x identifies the motif (1H, 2H, 3H, 1L, or 2L) and y is the residue number counting from x-C where the residue number of x-C is -1. For example, 1H-C(-2) is the second to last amino acid residue of the first alpha-helix. The binding protein includes a first solvent-exposed surface, a second solvent-exposed surface, a third solvent-exposed surface, and a fourth solvent-exposed surface. A solvent- exposed surface is a three dimensional region of the protein where at least the side chains of the amino acid residues are projecting into solvent; that is, away from interacting with other residues of the protein such that they are free to interact with a target. A solvent exposed surface may include the binding region or a portion of the binding region. The first solvent-exposed surface includes a first portion of the first alpha-helix. The second solvent-exposed surface that includes a first portion of the second alpha-helix. The third solvent-exposed surface that includes a second portion of the second alpha-helix and a first portion of the third alpha-helix. The fourth solvent-exposed surface that includes a second portion of the first alpha-helix and a third portion of the second alpha-helix. In one or more embodiments, the first portion of the first alpha-helix and the second portion of the first alpha- helix are the same. In other embodiments, the first portion of the first alpha-helix and the second portion of the first alpha-helix differ by one or more residues. In one or more embodiments, the first portion of the second alpha-helix and the second portion of the second alpha-helix are the same. In other embodiments, the first portion of the second alpha-helix and the second portion of the second alpha-helix differ by one or more residues. In one or more embodiments, the first portion of the second alpha-helix and the third portion of the second alpha-helix are the same. In other embodiments, the first portion of the second alpha-helix and the third portion of the second alpha-helix differ by one or more residues. In one or more embodiments, the second portion of the second alpha-helix and the third portion of the second alpha-helix are the same. In other embodiments, the second portion of the second alpha-helix and the third portion of the second alpha-helix differ by one or more residues. The binding protein also includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, at least a portion of the third solvent-exposed surface, or at least a portion of the fourth solvent-exposed surface. As used herein, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence is structurally similar to the potential sequence. For example, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence has 80% or greater, 85% or greater, 90% or greater, 95% or greater, or 100% sequence identity or sequence similarity to the parental sequence. Not all amino acids located in the binding region need to engage in binding interactions with the binding target. The binding region can be thought of and referred to as the variable region or paratope. In one or more embodiments, the binding region includes at least a portion of the first solvent-exposed surface. In one or more embodiments, the binding region includes at least a portion of the second-solvent exposed surface. In one or more embodiments, the binding region includes at least a portion of the third solvent0exposed surface. The first solvent-exposed surface includes at least a portion of the first alpha-helix. In one or more embodiments, the first solvent-exposed surface further includes at least a portion of the first loop. In one or more embodiments, the first solvent-exposed surface may include at least a portion of the N-terminal portion (e.g., the N-terminal residue of the protein). In one or more embodiments, the first solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, ten or fewer, nine or fewer, eight or fewer, seven or fewer, or six or fewer amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the binding region includes at least a portion of the first solvent-exposed surface. In one or more embodiments, the first solvent-exposed surface includes the N-terminal amino acid; 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid residues of the first alpha-helix, 1, 2, 3, 4, or 5 amino acid residues of the first loop, or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes: 1a) the N-terminal amino acid residue of the binding protein; 1b) eight amino acid residues of the first alpha-helix; 1c) one amino acid residue of the first loop; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes 1b and 1c. In one or more embodiments, the first solvent-exposed surface includes 1a, 1b, and 1c. In one or more embodiments, the first solvent-exposed surface includes: 1d) the N-terminal amino acid of the binding protein; 1e) the 1H-N(1), 1H-N(2), 1H-N(5), 1H-N(6), 1H-N(8), 1H-N(9), 1H-(11), and 1H- N(12) residues; 1f) the 1H-C(-1), 1H-C(-2), 1H-C(-4), 1H-C(-5), 1H-C(-8), 1H-C(-9), 1H-C(-11), and 1H-C(-12) residues; 1g) the 1L-N(1) residue of the first loop; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes 1e and 1g. In one or more embodiments, the first solvent-exposed surface includes 1f and 1g. In one or more embodiments, the first solvent-exposed surface includes 1d and 1e. In one or more embodiments, the first solvent-exposed surface includes 1d and 1f. In one or more embodiments, the first solvent-exposed surface includes 1d, 1e, and 1g. In one or more embodiments, the first solvent-exposed surface includes 1d, 1f, and 1g. In one or more embodiments, the binding region includes at least a portion of the first solvent-exposed surface. In one or more embodiments, the binding region include any combination of 1a through 1c or 1d through 1g such as those described herein. The second solvent-exposed surface includes at least a portion of the second alpha-helix. In one or more embodiments, the second solvent-exposed portion further includes a portion of the first, a portion of the second loop, or both. In one or more embodiments, the second solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid residues of the second alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the second loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes: 2a) one amino acid residue of the first loop; 2b) seven amino acid residues of the second alpha-helix; 2c) one amino acid residue of the second loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes 2a, 2b, and 2c. In one or more embodiments, the second solvent-exposed surface includes 2a and 2b. In one or more embodiments, the second solvent-exposed surface includes: 2d) the L2-C(-1) residue of the first loop; 2e) the 2H-N(1), 2H-N(2), 2H-N(3), 2H-N(5), 2H-N(6), 2H-N(7), 2H-N(9), and 2H- N(10) residues of the second alpha-helix; 2f) the 2L-N(1) residue of the third loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes 2d, 2e, and 2f. In one or more embodiments, the second solvent-exposed surface includes 2d and 2e. In one or more embodiments, the binding region includes at least a portion of the second solvent-exposed surface. In one or more embodiments, the binding region includes any combination of 2a through 2c or 2d through 2f such as those disclosed herein. The third solvent-exposed surface includes at least a portion of the second alpha-helix and at least a portion of the third alpha-helix. In one or more embodiments, the third solvent- exposed surface includes a portion of the first loop, a portion of the second loop, or both. In one or more embodiments, the third solvent-exposed surface includes 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amino acid residues of the second alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of second loop; 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 residues of the third alpha-helix, or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes: 3a) one residue of the first loop; 3b) four residues of the second alpha-helix; 3c) one or two residue of the second loop; 3d) four residues of the third alpha-helix; or any combination thereof. In one or more embodiments, the third solvent-exposed region includes 3a, 3b, 3c, and 3d. In one or more embodiments, the third solvent-exposed region includes 3a, 3b, and 3d. In one or more embodiments, the third solvent-exposed region includes 3b, 3c, and 3d. In one or more embodiments, the third solvent-exposed region includes 3b and 3d. In one or more embodiments, the third solvent-exposed surface includes: 3e) the 1L-C(-1) residue of the first loop; 3f) the 2H-N(1), 2H-N(2), 2H-N(5), and 2H-N(9) residues of the second alpha-helix; 3g) the 2L-N(1) and / or the 2L-C(-1) residues of the second loop; 3h) the 3H-N(1), 3H-N(4), 3H-N(5), and 3H-N(8) residues of the third alpha-helix; or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes 3e, 3f, 3g, and 3h. In one or more embodiments, the third solvent-exposed surface includes 3f, 3g, and 3h. In one or more embodiments, the third solvent-exposed surface includes 3f and 3g. In one or more embodiments, the binding region includes at least a portion of the third solvent-exposed surface. In one or more embodiments, the binding region include any combination of 3a through 3e or 3h through 3f, such as those described herein. The fourth solvent-exposed surface includes at least a portion of first loop. In one or more embodiments, the third solvent-exposed surface includes a portion of the first alpha-helix, a portion of the second alpha-helix, a portion of the C-terminal portion, or any combination thereof. In one or more embodiments, the fourth solvent-exposed surface includes 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the fourth solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, or 5 amino acid residues of second alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the C-terminal portion; or any combination thereof. In one or more embodiments, the fourth solvent-exposed surface includes: 4a) two residues of the first alpha-helix; 4b) one residue of the first loop; 4c) four residues of the second alpha-helix; 4d) the C-terminal residue of the binding protein; or any combination thereof. In one or more embodiments, the fourth solvent-exposed region includes 4a, 4b, 4c, and 4d. In one or more embodiments, the fourth solvent-exposed region includes 4a, 4b, and 4c. In one or more embodiments, the third solvent-exposed surface includes: 4e) the 1H-C(-1) and 1H-C(-2) residues of the first alpha-helix; 4f) the 1L-N(1) residue of the first loop; 4g) the 1L-C(-1) residue of the first loop; 4h) the 2H-N(1), 2H-N(2), 2H-N(4), and 2H-N(5) residues of the second alpha-helix; 4i) the C-terminal amino acid of the binding protein; or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes 4e, 4f, 4g, 4h, and 4i. In one or more embodiments, the third solvent-exposed surface includes 4e, 4g, 4h, and 4i. In one or more embodiments, the binding region includes at least a portion of the fourth solvent-exposed surface. In one or more embodiments, the binding region include any combination of 4a through 4d or 4e through 4i, such as those described herein. Tables 1 shows a table of a 43 amino acid binding protein layout (e.g., the number of amino acid residues involved in each secondary structure (SS)). Tables 1 shows the residue numbers of the N-terminus (N), the first alpha-helix (1H), the first loop (1L), the second alpha- helix (2H), the second loop (2L), the third alpha-helix (3H), and the C-terminus; the residue numbers of the first solvent-exposed surface (SES1), the second solvent-exposed surface (SES2), the third solvent-exposed surface (SES3), and the fourth solvent-exposed surface (SES4); as well as four binding regions (BR1-BR4). The binding protein may have 43 amino acids following the secondary structure residue layout Table 1 and may have any one of the solvent-exposed surfaces and / or binding regions of Table 1. Table 2 shows the binding residue numbers in reference to the secondary structure motifs for BR1 through BR4. In one or more embodiments, the binding proteins can be derived from the parental proteins of SEQ ID NO:1 (also called parent protein F, framework F, or scaffold F), SEQ ID NO:2 (also called parent protein G, framework G, or scaffold G), SEQ ID NO:3 (also called parent protein H, framework H, or scaffold H), SEQ ID NO:4 (also called parent protein I, framework I, or scaffold I), or SEQ ID NO:5 (also called parent protein J, framework J, or scaffold J) (see Table 3 for the sequences). SEQ ID NOs:1-5 are computationally designed hyperstable scaffolds designed by Rocklin et al. (Rocklin, G. J., Chidyausiku, T. M., Goreshnik, I., Ford, A., Houliston, S., Lemak, A., Carter, L., Ravichandran, R., Mulligan, V. K., Chevalier, A., Arrowsmith, C. H. & Baker, D. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ).357, 168–175 (2017)).^These proteins were designed to fold into the α3 topology, not necessarily to tolerate diversification or enable selective binding to a target. SEQ ID NOs:1-5 are 43 amino acid proteins following the secondary structure layout of Table 1. The consensus sequence of the framework sequences F, G, H, I, and J (SEQ ID NOs:1-5) is SEQ ID NO:6 (see Table 3). As such, a binding protein of the present disclosure may be derived from any one of parental proteins SEQ ID NOs:1-6 where at least one of the amino acid residues of any one of binding regions 1-4 (Table 1) is varied from the parental sequence. In one or more embodiments, the binding protein has a sequence that has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of SEQ ID NO:7, SEQ ID NO:8, SEQ ID NO:9, SEQ ID NO:10, SEQ ID NO:11, SEQ ID NO:12, SEQ ID NO:13, SEQ ID NO:14, SEQ ID NO:15, SEQ ID NO:16, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:19, SEQ ID NO:20, SEQ ID NO:21, SEQ ID NO:22, SEQ ID NO:23, SEQ ID NO:24, SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, or SEQ ID NO:30 (see Table 4 where each X is independently any amino acid). In SEQ ID NOs:5 – 36, X represents the binding region. Positions that have an X can be varied to develop binding to one or more targets. Each X can independently be any amino acid. In one or more embodiments, one or more of the Xs in a sequence can be A, C, D, G, N, S, T, or Y. For example, residue 17, residue 18, or both in Con α2(SEQ ID NO: 13), F α2(SEQ ID NO: 14), G α2(SEQ ID NO: 15), H α2(SEQ ID NO: 16), I α2(SEQ ID NO: 17), J α2(SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y. In one or more embodiments, one or more of the Xs in a sequence can be D, E, G, H, K, N, Q, R, or S. For example, in one or more embodiments, residue 21 in Con α2(SEQ ID NO: 13), F α2(SEQ ID NO: 14), G α2(SEQ ID NO: 15), H α2(SEQ ID NO: 16), I α2(SEQ ID NO: 17), J α2(SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one more embodiments, residue 17 and residue 18 in Con α2(SEQ ID NO: 13), F α2(SEQ ID NO: 14), G α2(SEQ ID NO: 15), H α2(SEQ ID NO: 16), I α2(SEQ ID NO: 17), J α2(SEQ ID NO: 18) is A, C, D, G, N, S, T, or Y and residue 21 in Con α2(SEQ ID NO: 13), F α2(SEQ ID NO: 14), G α2(SEQ ID NO: 15), H α2(SEQ ID NO: 16), I α2(SEQ ID NO: 17), J α2(SEQ ID NO: 18) is D, E, G, H, K, N, Q, R, or S. In one or more embodiments, one or more of the Xs in a sequence can be W. For example, in one or more embodiments, residue 43 of Con L1(SEQ ID NO: 25), F L1(SEQ ID NO: 26), G L1(SEQ ID NO: 27), H L1(SEQ ID NO: 28), I L1(SEQ ID NO: 29), J L1(SEQ ID NO: 30) is W. Table 4 shows the sequences of SEQ ID NOs:7-30. SEQ ID Nos.7-30 are 43 amino acid binding proteins that follow the same secondary structure layout as shown in Table 1. In Table 4, an F, G, H, I, J, or Con listed before α1; α2; α2,3; or L1indicates the sequence was derived from parental sequence framework F (SEQ ID NO:1), framework G ( SEQ ID NO:2), framework H (SEQ ID NO:3), framework I (SEQ ID NO:4), framework J (SEQ ID NO:5), or the framework consensus sequence (SEQ ID NO:6). In Table 4 α1; α2, α2,3, and L1are B1, B2, B3, and B4 from Table 1 and Table 2, respectively.

[0002] In one or more embodiments, the binding protein is any one of the binding proteins in Table 5 or a binding protein with a sequence that has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity thereto.

[0003] The binding proteins of the present disclosure bind to a target. The target may be a protein such as an enzyme, a transporter protein, a transmembrane protein, a receptor, or a structural protein. In one or more embodiments, the target is an intracellular target. In other embodiments, the target is an extracellular target. For example, in one or more embodiments, the target is a protein that is overexpressed by diseased cells and / or located on the surface of diseased cells. In one or more embodiments, the binding protein acts as an agonist (upregulates one or more functions of the target) or an antagonist (at least partially inhibits one or more functions of the target) to the target protein. In other embodiments, the binding protein simply recognizes the target protein. In some such embodiments, the binding protein or a binding compound containing the same can be used for imaging. The binding protein may bind to the target with a variety of dissociation constants (Kdor KD). In one or more embodiments, the binding protein binds a target with a Kdof 1 femtomolar (fM) or greater, 100 fM or greater, 500 fM or greater, 750 fM or greater, 1 picomolar (pM) or greater, 100 pM or greater, 500 pM or greater, 750 pM or greater, 1 nanomolar (nM) or greater, 50 nM or greater, 100 nM or greater, 500 nM or greater, or 750 nM or greater. In one or more embodiments, the binding protein binds a target with a Kdof 1 micromolar (μM) or less, 750 nM or less, 500 nM or less, 100 nM or less, 50 nM or less, 1 nM or less, 750 pM or less, 500 pM or less, 100 pM or less, 500 fM or less, or 100 fM or less. In one or more embodiments, the binding protein binds to a target with a Kdof 1 fM to 1 μM, 1 fM to 750 nM, 1 fM to 500 nM, 1 fM to 100 nM, 1 fM to 1 nM, 1fM to 750 pM, 1 fM to 500 pM, 1 fM to 100 pM, 1 fM to 1 pM, 1 fM to 750 fM, 1 fM to 500 fM, 1 fM to 100 fM, 100 fM to 1 μM, 100 fM to 750 nM, 100 fM to 500 nM, 100 fM to 100 nM, 100 fM to 1 nM, 100 fM to 750 pM, 100 fM to 500 pM, 100 fM to 100 pM, 100 fM to 1 pM, 100 fM to 500 fM, 100 fM to 750 fM, 500 fM to 1 μM, 500 fM to 750 nM, 500 fM to 500 nM, 500 fM to 100 nM, 500 fM to 1 nM, 500 fM to 750 pM, 500 fM to 500 pM, 500 fM to 100 pM, 500 fM to 1 pM,1 pM to 1 μM, 1 pM to 750 nM, 1 pM to 500 nM, 1 pM to 100 nM, 1 pM to 1 nM, 1 pM to 750 pM, 1 pM to 500 pM, 1 pM to 100 pM, 100 pM to 1 μM, 100 pM to 750 nM, 100 pM to 500 nM, 100 pM to 100 nM, 100 pM to 1 nM, 100 pM to 750 pM, 100 pM to 500 pM, 500 pM to 1 μM, 500 pM to 750 nM, 500 pM to 500 nM, 500 pM to 100 nM, 500 pM to 1 nM, 500 pM to 750 pM, 750 pM to 1 μM, 750 pM to 750 nM, 750 pM to 500 nM, 750 pM to 100 nM, 750 pM to 1 nM, 1 nM to 1 μM, 1 nM to 750 nM, 1 nM to 500 nM, 1 nM to 100 nM, 100 nM to 1 μM, 100 nM to 750 nM, 100 nM to 500 nM, 500 nM to 1 μM, 500 nM to 750 nM, or 750 nM to 1 μM. In one or more embodiments, the target is programmed cell death protein 1 (PD-1). In one or more embodiments, the target is cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). In one or more embodiments, the target is IGF1R. In one or more embodiments, the target is vascular endothelial growth factor (VEGF). VEGF is a crucial signal protein for blood vessel development, contributing to cancer tumor growth and progression, while also being associated with coronary heart disease, solidifying VEGF as a prime target for protein therapeutics. In one or more embodiments, where the binding protein targets and binds to VEGF, the binding protein has an amino acid sequence has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of α3J:α2:1 (SEQ ID NO:31), α3J:α2:2 (SEQ ID NO:32), α3J:α2: 3 (SEQ ID NO:33), α3J: α2:4 (SEQ ID NO:34), α3J:α2:5 (SEQ ID NO:35), α3J:α2:6 (SEQ ID NO:36), α3J:α2:7 (SEQ ID NO:37), α3J:α2:8 (SEQ ID NO:38), α3J:α2:9 (SEQ ID NO:39), α3J:α2:10 (SEQ ID NO:40), α3J: α2:11 (SEQ ID NO:41), α3J:α2:12 (SEQ ID NO:42), α3J:α2:13 (SEQ ID NO:43), α3J:α2:14 (SEQ ID NO:44), α3J:α2:15 (SEQ ID NO:45), α3J:α2:16 (SEQ ID NO:46), α3J:α2:17 (SEQ ID NO:47), α3J:α2:18 (SEQ ID NO:48), α3J:α2:19 (SEQ ID NO:49), α3J:α2:20 (SEQ ID NO:50), or α3J:α2:21 (SEQ ID NO:51). SEQ ID NOs:31-51 were derived from the parental protein sequence of framework protein J (SEQ ID NO:5). Additionally, SEQ ID NOs:31-51 were developed by varying the binding region BR2 of Table 1. In one or more embodiments, where the binding protein targets and binds to VEGF, the binding protein has an amino acid sequence has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to α3I:α2:1 (SEQ ID NO:52) or α3I:α2:2 (SEQ ID NO:53). SEQ ID NOs:52-53 were derived from the parental protein sequence of framework H (SEQ ID NO:3). Additionally, SEQ ID NOs:52-53 were developed by varying the binding region BR2 of Table 1. Binding proteins derived from proteins having four beta-strands and one alpha-helix In one or more embodiments, the binding protein is or is derived from a protein having a ββαββ tertiary structure. FIG.54 depicts the ββαββ tertiary structure of a binding protein 100. Binding protein 100 includes a beta-sheet 110, an alpha-helix 120, a N-terminal portion 105, a C- terminal portion 107, a first loop 130, a second loop 140, a third loop 150, and a fourth loop 160. FIG. 55 depicts the secondary structure and secondary structural components (e.g., beta-strands) of the binding protein 100 that fold into the tertiary structure of FIG.54. The beta-sheet (110 in FIG. 54) includes a first beta-strand 170, a second beta-strand 180, a third beta-strand 190, and a fourth beta-strand 200. The first beta-strand 170 is coupled to the second beta-strand 180 through the first loop 130. The second beta-strand 180 is coupled to the alpha-helix 120 through the second loop 140. The alpha-helix 120 is coupled to the third beta-strand 190 through the third loop 150. The third beta-strand 190 is coupled to the fourth beta-strand 200 through the fourth loop 160. A binding protein of the present disclosure may be of any suitable length. The length of the binding protein is the number of consecutive amino acid residues that form the ββαββ topology described herein. For example, in embodiments, where a binding protein is coupled to a second proteinaceous component and / or includes additional sequences on the C-terminal or N- terminal end (e.g., for purification purposes), the additional amino acids are not included in the length of the binding protein. The binding protein may be 30 amino acids or longer, 35 amino acids or longer, 36 amino acids or longer, 38 amino acids or longer, 39 amino acids or longer, 40 amino acids or longer, 41 amino acids or longer, 42 amino acids or longer, 43 amino acids or longer, 44 amino acids or longer, 45 amino acids or longer, 46 amino acids or longer, 50 amino acids or longer, or 55 amino acids or longer. The binding protein may be 60 amino acids or shorter, 55 amino acids or shorter, 50 amino acids or shorter, 46 amino acids or shorter, 45 amino acids or shorter, 44 amino acids or shorter, 43 amino acids or shorter, 42 amino acids or shorter, 41 amino acids or shorter, 40 amino acids or shorter, 39 amino acids or shorter, 38 amino acids or shorter, 36 amino acids or shorter, or 35 amino acids or shorter. In one or more embodiments, the binding protein is 30 to 60, 30 to 55, 30 to 50, 30 to 46, 30 to 45, 30 to 44, 30 to 44, 30 to 43, 30 to 42, 30 to 41, 30 to 40, 30 to 39, 30 to 38, 30 to 36, 36 to 60, 36 to 55, 36 to 50, 36 to 46, 36 to 45, 36 to 44, 36 to 44, 36 to 43, 36 to 42, 36 to 41, 36 to 40, 36 to 39, 36 to 38, 38 to 60, 38 to 55, 38 to 50, 38 to 46, 38 to 45, 38 to 44, 38 to 43, 38 to 42, 38 to 41, 38 to 40, 38 to 39, 39 to 60, 39 to 55, 39 to 50, 39 to 46, 39 to 45, 39 to 44, 39 to 44, 39 to 43, 39 to 42, 39 to 41, 39 to 40, 40 to 60, 40 to 55, 40 to 50, 40 to 46, 40 to 45, 40 to 44, 40 to 44, 40 to 43, 40 to 42, 40 to 41, 41 to 60, 41 to 55, 41 to 50, 41 to 46, 41 to 45, 41 to 44, 41 to 43, 41 to 42, 42 to 60, 42 to 55, 42 to 50, 42 to 46, 42 to 45, 42 to 44, 42 to 43, 43 to 60, 43 to 55, 43 to 50, 43 to 46, 43 to 45, 43 to 44, 44 to 60, 44 to 55, 44 to 50, 44 to 46, 44 to 45, 45 to 60, 45 to 55, 45 to 50, 45 to 46, 46 to 60, 46 to 55, 46 to 50, 50 to 60, 50 to 55, or 55 to 60 amino acids in length. The binding proteins of the present disclosure include an N-terminal portion (105). The N-terminal portion defines the N-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the N-terminus of the binding compound may not be the N-terminus of the binding protein. In one or more embodiments, the N-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the N-terminal portion includes one residue that is not a part of a secondary structure. The ability of the N-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids in that portion. The first beta-strand (1B; 170) includes the N-terminus of the binding protein or is directly C-terminal to the N-terminal portion of the binding protein. The first beta-strand has a first beta N-terminus (1B-N; 171) and a first beta C-terminus (1B-C; 172). In one or more embodiments, the first beta-strand defines the N-terminus. In such embodiments, the 1B-N defines the N-terminus of the binding protein. In one or more embodiments, the first beta-strand includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the first beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer residues. In one or more embodiments, the first beta-strand includes two, three, four, five, six, seven, eight, nine, or ten residues. The second beta-strand (2B; 180) includes a second beta N-terminus (2B-N; 181) and a second beta C-terminus (2B-C; 182). The 2B-N is the most N-terminal amino acid residue of the second beta-strand. The 2B-C is the most C-terminal amino acid residue of the second beta- strand. In one or more embodiments, the second beta-strand includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the second beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the second beta-strand includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The alpha-helix (H; 120) includes a helix N-terminus (H-N; 121) and a helix C-terminus (H-C; 122). The H-N is the most N-terminal amino acid residue of the alpha-helix. The H-C is the most C-terminal amino acid residue of the alpha-helix. In one or more embodiments, the alpha-helix includes 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acids residues. In one or more embodiments, the alpha-helix includes 20 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, 5 or fewer, or 4 or fewer amino acid residues. In one or more embodiments, the alpha-helix includes 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. The third beta-strand (3B; 190) includes a third beta N-terminus (3B-N; 191) and a third beta C-terminus (3B-C; 192). The 3B-N is the most N-terminal amino acid residue of the third beta-strand. The 3B-C is the most C-terminal amino acid residue of the third beta-strand. In one or more embodiments, the third beta-strand includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the third beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the third beta-strand includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The fourth beta-strand (4B; 200) includes a third beta N-terminus (4B-N; 201) and a third beta C-terminus (4B-C; 202). The 4B-N is the most N-terminal amino acid residue of the fourth beta-strand. The 4B-C is the most C-terminal amino acid residue of the fourth beta-strand. In one or more embodiments, the fourth beta-strand includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the fourth beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the fourth beta-strand includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The first loop (1L; 130) couples the first beta-strand (170) to the second beta-strand (180). The first loop includes a first loop N-terminus (1L-N; 131) and a first loop C-terminus (1L-C; 132). The 1L-N is the most N-terminal amino acid residue of the first loop. The 1L-C is the most C-terminal amino acid residue of the first loop. The 1L-N of the first loop is coupled to the 1B-C of the first beta-strand and the 1L-C is coupled to the 2L-N of the second beta-strand. In one or more embodiments, the first loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the first loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the first loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The second loop (2L; 140) couples the second beta-strand (180) to the alpha-helix (120). The second loop includes a second loop N-terminus (2L-N; 141 and a second loop C-terminus (2L-C; 42). The 2L-N is the most N-terminal amino acid residue of the second loop. The 2L-C is the most C-terminal amino acid residue of the second loop. The 2L-N of the first loop is coupled to the 2B-C of the second beta-strand and the 2L-C is coupled to the H-N of the alpha-helix. In one or more embodiments, the second loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the second loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the second loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The third loop (3L; 150) couples the alpha-helix (120) to the third beta-strand (190). The third loop includes a third loop N-terminus (3L-N; 151and a third loop C-terminus (3L-C, 154). The 3L-N is the most N-terminal amino acid residue of the third loop. The 3L-C is the most C- terminal amino acid residue of the third loop. The 3L-N of the third loop is coupled to the H-C of the alpha-helix and the 3L-C of the third loop is coupled to the to 3B-N of the third beta-strand. In one or more embodiments, the third loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the third loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the third loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The fourth loop (5L; 160) couples the third beta-strand (190) to the fourth beta-strand (200). The fourth loop includes a fourth loop N-terminus (4L-N; 151) and a fourth loop C- terminus (4L-C, 154). The 4L-N is the most N-terminal amino acid residue of the fourth loop. The 4L-C is the most C-terminal amino acid residue of the fourth loop. The 4L-N of the fourth loop is coupled to the 3B-C of the third beta-strand and the 4L-C of the fourth loop is coupled to the 4B-N of the fourth beta-strand. In one or more embodiments, the fourth loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the fourth loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the third loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. The C-terminal portion (107) defines the C-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the C-terminus of the binding compound may not be the C-terminus of the binding protein. In one or more embodiments, the C-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the C-terminal portion includes one amino acid that is not a part of a secondary structure. The ability of the C-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids. In one or more embodiments, the 4B-C of the fourth beta-strand defines the C-terminus. Specific amino acid residue locations within the first beta-strand, the first loop, the second beta-strand, the second loop, the alpha-helix, the third loop, the third beta-strand, the fourth loop, and the fourth beta-strand can be denoted by counting the amino acid residues from the N-terminal or C-terminal amino acid residue of a specified motif (e.g., the 1L-C, 2B-N, and so on). When counting residue numbers from the N-terminal amino acid residue of a specified motif, the residue may be identified as x-N(1+y) where x identifies the motif (1B, 2B, 3B, 4B, H, 1L, 2L, 3L, and 4L) and y is the residue number counting from x-N where the residue number of x-N is 1. For example, 1B-N(2) is the second amino acid residue in the first beta-strand. When counting residue numbers from the C-terminal amino acid residue of a specified motif, the residue may be identified as x-C(-1-y) where x identifies the motif (1B, 2B, 3B, 4B, H, 1L, 2L, 3L, and 4L) and y is the residue number counting from x-C where the residue number of x-C is - 1. For example, 1B-C(-2) is the second to last amino acid residue of the first beta-strand. The binding protein includes a first solvent-exposed surface, a second solvent-exposed surface, and a third solvent-exposed surface. A solvent-exposed surface is a three dimensional region of the protein where at least the side chains of the amino acid residues are projecting into solvent; that is, away from interacting with other residues of the protein such that they are free to interact with a target. The binding protein also includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, or at least a portion of the third solvent-exposed surface. As used herein, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence is structurally similar to the potential sequence. For example, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence has 80% or greater, 85% or greater, 90% or greater, 95% or greater, or 100% sequence identity or sequence similarity to the parental sequence. Not all amino acids located in the binding region need to engage in binding interactions with the binding target. The binding region can be thought of and referred to as the variable region or paratope. The first solvent-exposed surface includes at least a portion of the beta-sheet. In one or more embodiments, the first solvent-exposed surface includes at least a portion of the first beta- strand, second beta-strand, third beta-strand, fourth beta-strand, or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes a portion of the first loop, a portion of the third loop, a portion of the fourth loop, or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes the C-terminal residue of the binding protein. In one or more embodiments, the first solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the first solvent-exposed surface includes the N-terminal amino acid; 1, 2, 3, 4, or 5 amino acid residues of the first beta-strand; 1, 2, 3, 4, or 5, amino acid residues of the first loop; 1, 2, 3, 4, or 5 amino acid residues of the second beta-strand; 1, 2, 3, 4, or 5 amino acid residues of the third loop; 1, 2, 3, 4, or 5 amino acid residues of the third beta- strand; 1, 2, 3, 4, or 5 amino acid residues of the fourth loop; 1, 2, 3, 4, or 5 amino acid residues of the fourth beta-strand; the C-terminal amino acid of the binding protein; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes: 1a) the N-terminal amino acid residue of the binding protein; 1b) two amino acid residues of the first beta-strand; 1c) one amino acid residue of the first loop; 1d) two amino acid residues of the second beta-strand; 1e) one amino acid residue of the third loop; 1f) two amino acids of the third beta-strand; 1g) one amino acid residue of the fourth loop; 1h) two amino acid residues of the fourth beta-strand; 1i) the C-terminal residue of the binding protein; or any combination of 1a through 1i. In one or more embodiments, the first solvent-exposed surface includes 1b, 1c, and 1d. In one or more embodiments, the first solvent-exposed surface includes 1e, 1f, 1g, 1h, and 1i. In one or more embodiments, the first solvent-exposed surface includes 1b, 1c, 1d, 1e, 1f, 1g, 1h, and 1i . In one or more embodiments, the first solvent-exposed surface includes: 1j) the N-terminal amino acid of the binding protein; 1k(i)) the 1B-N(2) and 1B-N(4) residues of the first beta-strand; 1k(ii) the 1B-N(1) and 1B-N(3) residues of the first beta-strand; 1l) the 1L-N(3) residue of the first loop; 1m) the 2B-N(1) and 2B-N(3) residues of the second beta-strand; 1n) the 3L-N(3) residue of the third loop; 1o) the 3B-N(2) and 3B-N(4) residues of the third beta-strand; 1p) the 4L-N(2) residue of the fourth loop; 1q) the 4B-N(1) and 4-B(N3) residues of the fourth beta-strand; 1r) the C-terminal residue of the binding protein; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes 1k(i), 1l, and 1m. In one or more embodiments, the first solvent-exposed surface includes 1k(ii), 1l, and 1m. In one or more embodiments, the first solvent-exposed surface includes 1n, 1o, 1p, 1q, and 1r. In one or more embodiments, the first solvent-exposed surface includes 1k(i), 1l, 1m, 1n, 1o, 1p, 1q, and 1r. In one or more embodiments, the first solvent-exposed surface includes 1k(ii), 1l, 1m, 1n, 1o, 1p, 1q, and 1r. In one or more embodiments, the binding region includes at least a portion of the first solvent-exposed surface. In one or more embodiments, the binding region include any combination of 1a through 1i or 1j through 1r such as those described herein. The second solvent-exposed surface includes at least a portion of the alpha-helix. In one or more embodiments, the second solvent-exposed portion further includes a portion of the second loop, a portion of the third loop, or both. In one or more embodiments, the second solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the second loop; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues of the alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the third loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes: 2a) one amino acid residue of the second loop; 2b) eleven amino acid residues of the alpha-helix; 2c) one amino acid residue of the third loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes 2a, 2b, and 2c. In one or more embodiments, the second solvent-exposed surface includes 2b. In one or more embodiments, the second solvent-exposed surface includes: 2d) the L2-C(-1) residue of the second loop; 2e) the H-N(2), H-N(3), H-N(5), H-N(6), H-N(7), H-N(9), H-N(10), H-N(11), H-N(13), H-N(14), and H-N(15) residues of the alpha-helix; 2f) the 3L-N(1) residue of the third loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes 2d, 2e, and 2f. In one or more embodiments, the second solvent-exposed surface includes 2e. In one or more embodiments, the binding region includes at least a portion of the second solvent-exposed surface. In one or more embodiments, the binding region includes any combination of 2a through 2c or 2d through 2f such as those disclosed herein. The third solvent-exposed surface includes at least a portion of the first loop and at least a portion of the third loop. In one or more embodiments, the third solvent-exposed surface includes at least a portion of the alpha-helix. In one or more embodiments, the third solvent-exposed surface includes 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, or 5, amino acid residues of the alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the third loop; or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes: 3a) three residues of the first loop; 3b) one residue of the alpha-helix; 3c) three residues of the third loop; or any combination thereof. In one or more embodiments, the third solvent-exposed region includes 3a, 3b, and 3c. In one or more embodiments, the third solvent-exposed region includes 3a and 3c. In one or more embodiments, the third solvent-exposed surface includes: 3d) the L1-N(2), 1L-N(3), and 1L-N(4) residues for the first loop; 3e) the H-C(-1) residue of the alpha-helix; 3f) the L3-N(1) and L3-N(2) residues for the third loop; or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes 3d, 3e, and 3f. In one or more embodiments, the binding region includes at least a portion of the third solvent-exposed surface. In one or more embodiments, the binding region include any combination of 3a through 3c or 3d through 3f, such as those described herein. Table 6 shows a table of a 43 amino acid binding protein having two possible scaffold layouts (e.g., the number of amino acid residues involved in each secondary structure). For each scaffold layout, scaffold 1 and scaffold 2, Table 5 shows the residue numbers of the N-terminus (N), the first beta-strand (1B), the first loop (1L), the second beta-strand (2B), the second loop (2L), the alpha-helix (H), the third loop (3L), the third beta-strand (3B), the fourth loop (4L), the fourth beta-strand (4B), and the C-terminus; the residue numbers of the first solvent-exposed surface (SES1), the second solvent-exposed surface (SES2), and the third solvent-exposed surface (SES3); as well as five binding regions (BR1-BR5). The binding protein may have 43 amino acids following the secondary structure residue layout of scaffold 1 or scaffold 2 of Table 6 and may have any one of the solvent-exposed surfaces and / or binding regions of Table 6. Table 6 shows the binding residue numbers in reference to the secondary structure motifs for BR1 through BR5. Table 6:

[0004] Table 6 continued:

[0005] In one or more embodiments, the binding proteins can be derived from the parental proteins of SEQ ID NO:67 (also called parent protein A, framework A, or scaffold A), SEQ ID NO:68 (also called parent protein B, framework B, or scaffold B), SEQ ID NO:69 (also called parent protein C, framework C, or scaffold C), SEQ ID NO:70 (also called parent protein D, framework D, or scaffold D), or SEQ ID NO:71 (also called parent protein E, framework E, or scaffold E). SEQ ID NOs:67-71 are computationally designed hyperstable scaffolds designed by Rocklin et al. (Rocklin, G. J., Chidyausiku, T. M., Goreshnik, I., Ford, A., Houliston, S., Lemak, A., Carter, L., Ravichandran, R., Mulligan, V. K., Chevalier, A., Arrowsmith, C. H. & Baker, D. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ).357, 168–175 (2017)).^These proteins were designed to fold into the ββαββ topology, not necessarily to tolerate diversification or enable selective binding to a target. SEQ ID NOs:67-71 are 43 amino acid proteins following the secondary structure layout of Table 6. The proteins of SEQ ID NO:67, SEQ ID NO:68, and SEQ ID NO:71 follow the scaffold 1 layout of Table 6. The proteins of SEQ ID NO:69 and SEQ ID NO:70 follow the scaffold 2 layout of Table 6. The consensus sequence of SEQ ID NOs:67-71 is SEQ ID NO:72. As such, a binding protein of the present disclosure may be derived from any one of parental proteins SEQ ID NOs:67-72 where at least one of the amino acid residues of any one of binding regions 1-5 (Table 7) is varied from the parental sequence. In one or more embodiments, the binding protein of the present disclosure may be derived from any one of the framework sequences in Table 8. In one or more embodiments, the binding protein has a sequence that has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of the sequences in Table 9. In one or more embodiments, the binding protein has a sequence that has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of SEQ ID NO:73, SEQ ID NO:74, SEQ ID NO:75, SEQ ID NO:76, SEQ ID NO:77, SEQ ID NO:78, SEQ ID NO:79, SEQ ID NO:80, SEQ ID NO:81, SEQ ID NO:82, SEQ ID NO:83, SEQ ID NO:84, SEQ ID NO:85, SEQ ID NO:86, SEQ ID NO:87, SEQ ID NO:88, SEQ ID NO:89, SEQ ID NO:90, SEQ ID NO:91, SEQ ID NO:92, SEQ ID NO:93, SEQ ID NO:94, SEQ ID NO:96, SEQ ID NO:97, SEQ ID NO:98, SEQ ID NO:99, SEQ ID NO:100, or SEQ ID NO:102 (see Table 9 where each X is independently any amino acid). In SEQ ID NOs:73 – 102, X may represent amino acids in the binding region. In some embodiments, one or more of the Xs in a sequence can be G or S. For example, in one or more embodiments, the fourth residue (first X residue) in A L2(SEQ ID NO: 98), B L2(SEQ ID NO: 99), C L2(SEQ ID NO: 100, D L2(SEQ ID NO: 101), or E L2(SEQ ID NO: 102) can be G or S. Positions that have an X can be varied to develop binding to one or more targets. Table 9 shows the sequences of SEQ ID NOs:73-102. SEQ ID Nos. 73-102 are 43 amino acid binding proteins that follow the same secondary structure layout as shown in Table 6. In Table 9, an A, B, C, D, E, or Con listed before α; β1,2; β2,3; β1-4; or L2indicates the sequence was derived from parental sequence framework A (SEQ ID NO:67), framework B (SEQ ID NO:68), framework C (SEQ ID NO:69), framework D (SEQ ID NO:70), framework E (SEQ ID NO:71), or the framework consensus sequence (SEQ ID NO:72), respectively. In Table 8, α; β1,2; Β2,3; Β1-4; and L2are BR1, BR2, BR3, BR4, and BR5 from Table 6 and Table 7, respectively.

[0006] In one or more embodiments, the binding protein is any one of the binding proteins in Table 10 or a binding protein with a sequence that has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity thereto. The binding proteins of the present disclosure bind to a target. The target may be a protein such as an enzyme, a transporter protein, a transmembrane protein, a receptor, or a structural protein. In one or more embodiments, the target is an intracellular target. In other embodiments, the target is an extracellular target. For example, in one or more embodiments, the target is a protein that is overexpressed by diseased cells and / or located on the surface of diseased cells. In one or more embodiments, the binding protein acts as an agonist (upregulates one or more functions of the target) or an antagonist (at least partially inhibits one or more functions of the target) to the target protein. In other embodiments, the binding protein simply recognizes the target protein. In some such embodiments, the binding protein or a binding compound containing the same can be used for imaging. The binding protein may bind to the target with a variety of dissociation constants (Kdor KD). In one or more embodiments, the binding protein binds a target with a Kdof 1 femtomolar (fM) or greater, 100 fM or greater, 500 fM or greater, 750 fM or greater, 1 picomolar (pM) or greater, 100 pM or greater, 500 pM or greater, 750 pM or greater, 1 nanomolar (nM) or greater, 50 nM or greater, 100 nM or greater, 500 nM or greater, or 750 nM or greater. In one or more embodiments, the binding protein binds a target with a Kdof 1 micromolar (μM) or less, 750 nM or less, 500 nM or less, 100 nM or less, 50 nM or less, 1 nM or less, 750 pM or less, 500 pM or less, 100 pM or less, 500 fM or less, or 100 fM or less. In one or more embodiments, the binding protein binds to a target with a Kdof 1 fM to 1 μM, 1 fM to 750 nM, 1 fM to 500 nM, 1 fM to 100 nM, 1 fM to 1 nM, 1fM to 750 pM, 1 fM to 500 pM, 1 fM to 100 pM, 1 fM to 1 pM, 1 fM to 750 fM, 1 fM to 500 fM, 1 fM to 100 fM, 100 fM to 1 μM, 100 fM to 750 nM, 100 fM to 500 nM, 100 fM to 100 nM, 100 fM to 1 nM, 100 fM to 750 pM, 100 fM to 500 pM, 100 fM to 100 pM, 100 fM to 1 pM, 100 fM to 500 fM, 100 fM to 750 fM, 500 fM to 1 μM, 500 fM to 750 nM, 500 fM to 500 nM, 500 fM to 100 nM, 500 fM to 1 nM, 500 fM to 750 pM, 500 fM to 500 pM, 500 fM to 100 pM, 500 fM to 1 pM,1 pM to 1 μM, 1 pM to 750 nM, 1 pM to 500 nM, 1 pM to 100 nM, 1 pM to 1 nM, 1 pM to 750 pM, 1 pM to 500 pM, 1 pM to 100 pM, 100 pM to 1 μM, 100 pM to 750 nM, 100 pM to 500 nM, 100 pM to 100 nM, 100 pM to 1 nM, 100 pM to 750 pM, 100 pM to 500 pM, 500 pM to 1 μM, 500 pM to 750 nM, 500 pM to 500 nM, 500 pM to 100 nM, 500 pM to 1 nM, 500 pM to 750 pM, 750 pM to 1 μM, 750 pM to 750 nM, 750 pM to 500 nM, 750 pM to 100 nM, 750 pM to 1 nM, 1 nM to 1 μM, 1 nM to 750 nM, 1 nM to 500 nM, 1 nM to 100 nM, 100 nM to 1 μM, 100 nM to 750 nM, 100 nM to 500 nM, 500 nM to 1 μM, 500 nM to 750 nM, or 750 nM to 1 μM. In one or more embodiments, the target is programmed cell death protein 1 (PD-1). In one or more embodiments, the target is cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). In one or more embodiments, the target is IGF1R. In one or more embodiments, the target is vascular endothelial growth factor (VEGF). VEGF is a crucial signal protein for blood vessel development, contributing to cancer tumor growth and progression, while also being associated with coronary heart disease, solidifying VEGF as a prime target for protein therapeutics. In one or more embodiments, where the binding protein targets and binds to VEGF, the binding protein has an amino acid sequence has 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of β2αβ2D β1-4: 1 (SEQ ID NO:103), β2αβ2D β1-4: 2 (SEQ ID NO:104), β2αβ2D β1-4: 3 (SEQ ID NO:105), or β2αβ2D β1-4: 4 (SEQ ID NO:106). β2αβ2D β1-4: 1-4 were derived from the parental protein sequence of SEQ ID NO:70. Additionally, β2αβ2D β1-4: 1-4 were developed by varying the binding region BR4 of Table 7. Experimental binding proteins that have and / or are derived from proteins having a three-helix bundle and experimental binding proteins that have and / or are derived from proteins having a having four beta-strands and one alpha-helix Example 1 describes the experimental methods used to produce and test the binding proteins that have and / or are derived from proteins having a three-helix bundle and binding proteins that have and / or are derived from proteins having a having four beta-strands and one alpha-helix. Forty-five combinatorial libraries that systematically vary in topology, framework sequence (parental sequence), and paratope locations was designed. Evolvability was measured via binder discovery to four diverse targets and developability was measured via four high- throughput assays. Through deep sequencing analysis validated by statistical testing, an array of evolvability and developability across design space was measured to identify drivers of performance. Although a hyperstable framework and localized diversity are insufficient criteria for an effective scaffold, select synthetic miniproteins, originally designed solely for foldedness, indeed serve as developable, evolvable scaffolds. To evaluate the effect of topology, framework sequence (parental sequence), paratope structure (binding region structure), and paratope sequence (binding region sequence) on binding protein scaffold evolvability and developability, each of these elements were systematically varied in a set of small (43 amino acids) synthetic scaffolds and measured protein performance. Two topologies – a triple-helix bundle (α3) and another with two pairs of anti-parallel beta- strands surrounding a central alpha-helix (β2αβ2) – to provide a range of structural paratope options (FIG.1; see Table 3 for sequences and variable regions). Five framework sequences for each topology were chosen. For the triple-helix bundle (α3) (FIG. 3), the frameworks included framework F (SEQ ID NO: 1), framework G (SEQ ID NO:2), framework H (SEQ ID NO: 3), framework I (SEQ ID NO: 4), and framework J (SEQ ID NO: 5) where the consensus sequence for frameworks F, G, H, I, and J is shown in FIG. 3. For the alpha-helix (β2αβ2) (FIG. 2), the frameworks included framework A (SEQ ID NO:67), framework B (SEQ ID NO:68), framework C (SEQ ID NO:69), framework D (SEQ ID NO:70), and framework E (SEQ ID NO:71) where the consensus sequence of frameworks A, B, C, D, and E is shown in FIG.2. Each framework for the α3topology and β2αβ2topology were chosen had high stability were chosen from a set of synthetic designs (Rocklin, G. J. et al. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ).357, 168–175 (2017)). Five distinct paratope locations were chosen for β2αβ2: the α-helical surface (α), exterior sites on β-strands 1 and 2 (β1,2), or 3 and 4 (β3,4), or 1-4 (β1-4), or two loops (L2); four distinct paratopes were chosen for α3: the surface of either helix 1, 2, or 2 and 3, or a single loop. As such, forty-five combinatorial libraries were created in total (FIG.1). For each paratope, sites were diversified to all 20 natural amino acids with the exception that areas connecting secondary structures were moderately constrained (FIG.2). Forty-five combinatorial libraries across these topologies, frameworks, and paratope sites were synthesized. Genetic libraries were transformed into a yeast surface display system to achieve a genotype-phenotype linkage for high-throughput selection for binding function (i.e. evolvability) and evaluation of developability. Transformation into yeast yielded 23 ± 5 million variants per sublibrary for a total merged library size of 1.0 billion variants.. Deep sequencing revealed that the constructed libraries match designs with a 0.8% absolute median deviation of amino acid frequency at each site (FIG.22). To identify functional scaffolds and evaluate how the choice of topology, framework, and paratope locations affect scaffold evolvability, all 45 libraries were pooled and sorted for binders to four distinct targets: programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte- associated protein 4 (CTLA-4), vascular endothelial growth factor (VEGF), and insulin-like growth factor receptor 1 (IGF1R). These biologically- and clinically relevant targets were chosen to provide differences in structure and size to aid in assessing the generality of the overall library evolvability. Three rounds of selections were performed to identify binders to each target immobilized on magnetic beads while depleting non-specific binders to beads coated in streptavidin or immunoglobulin G. Enrichment of target-specific binding was observed in all four target campaigns (FIG.23). The resulting populations were deep sequenced to assess the ability of each topology, framework, and paratope to yield specific binders. Evolvability was scored based on the quantity and quality of functional variants, i.e., number of unique binders and binding strength of the variants, quantified as the logarithmic enrichment of binder frequency compared to the unsorted population (detailed in the Example 1). Several scaffold library designs exhibited high evolvability with numerous binders to multiple targets (FIG.4 and FIG. 5). The most evolvable library design comprised diversification of 8 sites in the loop connecting helices 2 and 3 (FIG. 3, paratope L1) in clone J of the ჴ3bundle, which enabled discovery of 122 – 1,204 binders to each target. Other paratope locations were also evolvable in this framework, as evolution of helix 1, helix 2, or a combination of helices 2 and 3 all yielded specific binders to all four targets (FIG.4). The β2αβ2topology was also capable of high evolvability as diversification of 12 sites on the surface of the four β-strands (termed β1-4) of the clone β2αβ2A yielded binders to all four targets. This full β-sheet paratope was the most broadly effective across frameworks, as all five β2αβ2frameworks exhibited high evolvability to all four targets with this paratope location (FIG.5, FIG.8). Yet, hyperstable frameworks in these two topologies were not sufficient criteria for evolvability as there were many combinations of frameworks and paratopes that did not enable effective evolution of specific binders (FIG.4, FIG.5). Across the frameworks, paratopes, and targets tested, the β2αβ2topology was more evolvable than α3(FIG.6). A driver of this outcome was differential performance of framework sequences. Four of five β2αβ2 frameworks were enriched as contrasted by only one of five α3frameworks, two of which (F and G) had very minimal evolvability (FIG.7). Paratope structures exhibit a range of evolvability (FIG.8). Diversification of surface sites on all four β strands was highly effective within the β2αβ2topology, while diversifying only pairs of β strands was also effective. The loop paratope was the least evolvable location in the β2αβ2topology and also depleted in the α3topology. The first helix was the only enriched paratope in the α3topology. The variable evolvability of the two-helix paratope (ჴ2,3) is notable in comparison to the efficacy of the affibody, which is an effective ligand scaffold diversifying two adjacent helices in a three-helix bundle. Yet, the precise bundle topology, including helical length and orientation is distinct between the scaffolds as is the framework sequence (notably, ჴ3:J:ჴ2,3is highly evolvable) and diversity design (which has been optimized for affibody). Strikingly, diversification of the second helix (α2paratope) of the α3 bundles exhibited minimal binders in the F and G frameworks, as well as for three of four targets in the I framework, but was strongly enriched in the J framework with 83 - 552 binders to each target. This contextual dependence of evolutionary performance extended to molecular targets as the effect of topology was target-dependent as CTLA-4 and PD-1 are 2.1-fold and 1.7-fold preferentially targeted by libraries within the β2αβ2topology whereas α3libraries are 2.0-fold and 1.5-fold more enriched for binding IGF1R and VEGF (FIG.24). Along with primary function (i.e., binding), scaffolds may also exhibit biophysical robustness. The pooled libraries were evaluated for multiple metrics of developability using a set of library-scale assays. These flow cytometric assays measure protease resistance and thermal stability in a yeast display format and soluble expression in a split-GFP format, which have demonstrated utility to proxy for protein developability (see Example; Golinski, A. W. et al. High-throughput developability assays enable library-scale identification of producible protein scaffold variants. bioRxiv 1–11 (2020) doi:10.1101 / 2020.12.14.422755). Protease resistance is a valuable property for therapeutics and in vivo diagnostics and also proxies for other metrics of developability. The yeast-displayed scaffold variants are exposed to the relatively non-specific proteases proteinase K or thermolysin at 37 ºC or 55 ºC (see Example 1). The presence of epitope tags at the N-terminus and C-terminus of the scaffolds are then quantified for each cell via flow cytometry with anti-epitope antibodies (see Example). Protease-resistant variants exhibit a high C-terminal:N-terminal signal ratio whereas proteolysis of less stable variants reduces the presence of C-terminal epitopes thereby decreasing the ratio. Library variants were sorted via FACS into eight tiered gates to stratify fitness (FIG.25, FIG.26, and FIG.27). The split-GFP assay measures stable, soluble protein expression via genetic fusion of the scaffold variant to the 11thbeta-strand of GFP. Co-expression of the remainder of GFP enables protein recombination and fluorescent signal proportional to scaffold-GFP11expression. Library variants were sorted via FACS into six tiered gates to stratify fitness (FIG.28). Scores were calculated using a gate- weighted dot product, normalized to an unsorted population, using deep sequencing data from gated populations (see Example 1). The effect of the framework sequence on protease stability across several paratope libraries with diverse sets of sequences was evaluated and a range of performances was observed. Two frameworks, one within each topology, were the most protease stable: α3H (α3topology with framework H and β2αβ2B (β2αβ2topology with framework B; see FIG.9). Aggregated across paratopes, α3H exhibited stability 1.6x standard deviations above the mean and was significantly more stable (p < 7 u 10-5) than 8 of 9 other frameworks at 37 ºC and all 9 other frameworks (p < 3 u 10-4) at 55 ºC (FIG.29). β2αβ2B exhibited stability 1.0 standard deviation higher than the mean and was significantly more stable to proteinase K than all 7 frameworks (aside from α3H) at 37 ºC (p < 1 u 10-4); and five of 7 frameworks at 55 ºC. The reduced relative stability of β2αβ2B at 55 ºC suggests that this framework is more protease stable than thermally stable relative to other frameworks (FIG.29). α3G is the least proteinase K resistant framework at 37 ºC (p < 9 u 10-10). The other seven frameworks exhibited near-neutral scores. The effect of paratope location on protease stability across multiple frameworks for each paratope type was evaluated (FIG.10, FIG.30). Diversification of the surface of the third and fourth strands of β2αβ2(β2αβ2:β3,4) results in the most stability; further diversification of the first and second strands nominally decreases stability but the resultant variants remain enriched. The two paratopes that result in the least protease stability are the surface of the α helix (β2αβ2:α) and the loops (β2αβ2:L2) of β2αβ2. Notably, the highly protease stable outliers in both topologies come from the α3:H and β2αβ2:B frameworks. There is a high correlation between stability to protease K at 37 ºC and 55 ºC which is consistent with minimal differential thermal stress in this temperature range (FIG. 33). Notably, α3scaffolds consistently exhibit higher thermal stability (ratio of stability at 55 ºC vs.37 ºC) than β2αβ2scaffolds. Thermolysin, another broad-spectrum protease, was used to investigate the generalizability of framework / paratope effect on protease stability (see Example 1). The most stable framework in the protease K assay, α3H, proved to be the most stable against thermolysin (FIG.29 and FIG.31). The second-most stable framework in the proteinase K context, β2αβ2B, was moderately resistant against thermolysin. Other frameworks consistently exhibit moderate stability to both proteases. The paratope most resistant to protease K, β2αβ2:β3,4, was moderately stable to thermolysin (FIG.30 and FIG.32). Of the two paratopes least resistant to protease K, both within the β2αβ2topology, one (the α paratope) was also least stable to thermolysin whereas the other (L2paratope) exhibited moderate thermolysin stability. Overall, protease K vs. thermolysin results exhibit moderate correlation (ρ = 0.37) indicative of a related ability to proxy for conformational stability while also providing independent utility (FIG. 34). To expand the developability assessment, soluble bacterial expression of 105variants was measured from each of the 45 libraries via a split-GFP assay (see Example 1). A library with clones in the top gate (with a score of 2; FIG.11 and FIG.12) indicates that they are 100-fold more expressible than a library with clones collected in the bottom gate (with a score of -2). Sequence analysis indicated that framework sequences exhibited significantly different soluble expression (FIG. 11). α3F, the highest expresser when averaging across all paratope diversification libraries, exhibited 10- to 15-fold higher expression than α3J, the least expressed framework. Each framework exhibited multimodal distribution of soluble expression across different paratope diversifications which highlights the importance of paratope location in assessment of soluble expression. When aggregating across framework sequences, libraries varying in their paratope location vary widely in their soluble expression (FIG.12). Loop diversification is effectively tolerated in the β2αβ2topology, especially in the C and D frameworks. Conversely, α-helix diversifications result in very poor soluble expression in the β2αβ2topology. Combined with poor stability, the results indicate that the α-helix is critical to the overall developability for this topology. Collectively, the protease stability assays, with the two proteases and thermal stress, and the split-GFP soluble expression assay provide multiple metrics on protein developability for the topologies, frameworks, and paratopes evaluated. As these metrics are distinct, differential performance is achieved in different assays for many combinations. Yet, the α3H framework is consistently strong with the highest protease stability across conditions and a moderately high soluble expression (FIG. 13). The α3F and β2αβ2D frameworks are relatively robust with moderate protease stability across conditions and the highest soluble expression. At the other end of the spectrum, diversification of the α-helix in the β2αβ2topology consistently yields the poorest performance. As useful proteins may be developable and functional, the ability to achieve both outcomes within a single design was evaluated. All of the developability and evolvability metrics were combined into one score for each by taking the mean of the four protease, thermal, and expression assays and median of the four target evolvabilities, respectively. Previous studies have demonstrated a tradeoff between function and stability in single molecules. The combined performance is similarly challenging within the context of diversified distributions as only 13% of sublibrary designs (6 of 45) exhibit mutual enrichment for evolvability and developability (FIG.14). Yet, several combinations of topology, framework, and paratope exhibit a balance of good developability and evolvability and thereby serve as promising scaffold libraries. Scaffold α3J:α2exhibits the second highest evolvability of all 45 designs along with a developability score in the top 20%. β2αβ2B:β1,2is another promising scaffold with balanced developability and evolvability in the top 16% in both categories. Multiple other combinations of topology, framework, and paratope provide compelling opportunities including two additional paratope diversities within the α3J framework, multiple additional β2αβ2designs with balanced developability and evolvability, and four highly developable α3H designs, including one with elevated evolvability. Interestingly, while stability has previously been shown to aid clonal evolution, relying solely on the hyperstability of these four parental sequences does not ensure the designed library will provide a substantial number of high performing variants. Site-specific amino acid preferences that dictated developability and evolvability in these scaffolds were evaluated. Such preferences would elucidate performance and empower constrained library design. Sitewise amino acid enrichment was computed across the four evolutionary campaigns and four developability assays for the two most promising scaffold libraries, α3J:α2(FIG.15, FIG.16, and FIG.35). While many site / amino acid combinations had conflicting effects on evolvability and developability (FIG.15), there were also multiple examples that consistently aid performance (N19, Y22, M27 in α3J:α2and W2, V4, P7 in β2αβ2B:β1,2) or consistently hinder performance (K19, M22, T23 in α3J:α2and G4 in β2αβ2B:β1,2). The analysis was extended to evaluate amino acids’ effect on developability independent of site. Proline, glycine, alanine, asparagine, and aspartic acid exhibit a strong negative correlation with protease stability (FIG.16, FIG. 36). Proline provides a unique conformational constraint, which could enrich destabilized conformations. Conversely, glycine could provide excessive flexibility thereby enabling protease accessibility. Hydrophobic amino acids generally aid stability and soluble expression in these scaffolds and show a positive correlation. Random mutagenesis was performed on the scaffolds selected for VEGF binding and sorted the resultant variants via MACS and FACS to identify the strongest binding clones. The binding population was then subjected to proteinase K at 55 ºC and sorted via FACS to collect the top 5% of cells to find the most developable clones (see Example 1). Deep sequencing revealed multiple highly enriched variants from three distinct libraries (FIG.37 where β2αβ2D β1-4: 1 is SEQ ID NO:37; β2αβ2D β1-4: 2 is SEQ ID NO:38; β2αβ2D β1-4: 3 is SEQ ID NO:39; or β2αβ2D β1-4: 4 is SEQ ID NO:39). Random mutagenesis was performed on the variants selected for VEGF binding and sorted the resultant mutants via magnetic bead and flow cytometric selections to identify the strongest binding clones. The binding population was then subjected to proteinase K at 55 ºC and sorted via flow cytometry to collect the top 5% of cells to find the most developable clones. Deep sequencing revealed multiple highly enriched variants from three distinct libraries (FIG. 37). Twenty-four clones were expressed in an unoptimized shake flask E. coli culture and purified from the soluble lysate fraction. Recombinant yields were 2.6 ± 1.9 mg / L (range: 0 – 6 mg / L, FIG.17). The 16 clones with highest yield were evaluated by circular dichroism and AlphaFold2 (Jumper, J. et al. Highly accurate protein structure prediction with AlphaFold. Nature (2021) doi:10.1038 / s41586-021-03819-2) to assess structure. Circular dichroism revealed these clones to exhibit secondary structure consistent with their parental topology (FIG.38, FIG. 39, FIG. 40, FIG.41, FIG.100, and FIG. 101). AlphaFold2 predicts tertiary structures consistent with the parental topology (FIG. 21, FIG.46, FIG.47, FIG.48, FIG. 49, FIG. 50, FIG.51, and FIG. 104). Thermal treatment indicates midpoints of thermal denaturation of 78 ºC to >95 ºC (FIG.17, FIG.46, FIG.47, and FIG. 48, FIGS.42-45) as well as a return to their original structure when cooled to 25 °C after 95 ºC incubation indicating reversible denaturation (FIG. 18, FIG. 19, FIG.102, and FIG.103). Lastly, the binding affinities for four clones were measured via VEGF titrations. In addition to being very stable, the molecules had strong binding affinities with the lowest having sub-nanomolar KD(FIG.20, FIG.46, FIG.47, FIG.48, FIG. 104). The effect of topology, framework, and paratope was systematically evaluated on developability and evolvability of synthetic mini-proteins originally designed for stability. Starting parental framework stability and a localized diverse paratope are not sufficient criteria for high-performance scaffolds as most designs yielded limited developability and / or evolvability. Yet, multiple designs whose variant libraries exhibited high stability, moderate expression, and numerous selective binders across multiple targets were developed. The observed performance is especially striking given the moderate library size for each sublibrary (27 million). Moreover, the lead molecules were performant without affinity maturation, and a single round of random mutagenesis yielded subnanomolar binding while maintaining thermal stabilities >95 ºC. Binding proteins derived from proteins having three beta-strands and one alpha-helix In one or more embodiments, the binding proteins include or are derived from a parental sequence that includes a β-sheet and an α-helix secondary structure motifs that fold into a tertiary structure having an N-terminus to C-terminus βαββ (also called BABB, babb, and EHEE) topology where each β is a beta-strand and α is an alpha helix. The binding proteins include a parental amino acid sequence that has regions of variability (i.e., binding regions as discussed herein) where the regions of variability can be engineered to bind to a specific target. FIG.97 depicts the βαββ tertiary structure of a binding protein 200. The binding protein 200 includes a beta-sheet 210, an alpha-helix 220, a N-terminal portion 205, a C-terminal portion 207, a first loop 230, a second loop 240, and a third loop 250. FIG.98 depicts the secondary structures of the binding protein 200 that fold into the tertiary structure of FIG.97. The beta sheet (210 in FIG.97) includes a first beta-strand 260, a second beta-strand 280, and a third beta- strand 290. The binding protein further includes an alpha-helix 220. The first beta-strand 260 and the alpha-helix 220 are coupled by the first loop 230. The alpha-helix 220 and the second beta- strand 280 are coupled by the second loop 240. The second beta-strand 280 and the third beta- strand 290 are coupled by the third loop 250. A binding protein of the present disclosure may be a variety of lengths. The length of the binding protein is the number of consecutive amino acids residues that form the βαββ tertiary structure described herein. For example, in embodiments, where a binding protein is coupled to a second proteinaceous component and / or includes additional sequences on the C-terminal or N- terminal end (e.g., for purification purposes), the additional amino acids are not included in the length of the binding protein. The binding protein may be 30 amino acids or longer, 31 amino acids or longer, 32 amino acids or longer, 34 amino acids or longer, 35 amino acids or longer, 36 amino acids or longer, 38 amino acids or longer, 39 amino acids or longer, 40 amino acids or longer, 41 amino acids or longer, 42 amino acids or longer, 43 amino acids or longer, 44 amino acids or longer, 45 amino acids or longer, 46 amino acids or longer, 50 amino acids or longer, or 55 amino acids or longer. The binding protein may be 60 amino acids or shorter, 55 amino acids or shorter, 50 amino acids or shorter, 46 amino acids or shorter, 45 amino acids or shorter, 44 amino acids or shorter, 43 amino acids or shorter, 42 amino acids or shorter, 41 amino acids or shorter, 40 amino acids or shorter, 39 amino acids or shorter, 38 amino acids or shorter, 36 amino acids or shorter, 35 amino acids or shorter, 34 amino acids or shorter, 33 amino acids or shorter, 32 amino acids or shorter, or 31 amino acids or shorter. In one or more embodiments, the binding protein is 30 to 60, 30 to 55, 30 to 50, 30 to 46, 30 to 45, 30 to 44, 30 to 44, 30 to 43, 30 to 42, 30 to 41, 30 to 40, 30 to 39, 30 to 38, 30 to 36, 36 to 60, 36 to 55, 36 to 50, 36 to 46, 36 to 45, 36 to 44, 36 to 44, 36 to 43, 36 to 42, 36 to 41, 36 to 40, 36 to 39, 36 to 38, 38 to 60, 38 to 55, 38 to 50, 38 to 46, 38 to 45, 38 to 44, 38 to 43, 38 to 42, 38 to 41, 38 to 40, 38 to 39, 39 to 60, 39 to 55, 39 to 50, 39 to 46, 39 to 45, 39 to 44, 39 to 44, 39 to 43, 39 to 42, 39 to 41, 39 to 40, 40 to 60, 40 to 55, 40 to 50, 40 to 46, 40 to 45, 40 to 44, 40 to 44, 40 to 43, 40 to 42, 40 to 41, 41 to 60, 41 to 55, 41 to 50, 41 to 46, 41 to 45, 41 to 44, 41 to 43, 41 to 42, 42 to 60, 42 to 55, 42 to 50, 42 to 46, 42 to 45, 42 to 44, 42 to 43, 43 to 60, 43 to 55, 43 to 50, 43 to 46, 43 to 45, 43 to 44, 44 to 60, 44 to 55, 44 to 50, 44 to 46, 44 to 45, 45 to 60, 45 to 55, 45 to 50, 45 to 46, 46 to 60, 46 to 55, 46 to 50, 50 to 60, 50 to 55, or 55 to 60 amino acids in length. The binding proteins of the present disclosure include an N-terminal portion (205), a C- terminal portion (207), a beta-sheet (210), an alpha-helix (220), a first loop (230), a second loop (240), and a third loop (250). The beta sheet includes a first beta-strand (260), a second beta- strand (280), and a third beta-strand (290). The binding protein also includes a first solvent- exposed surface, a second solvent-exposed surface, and a third solvent-exposed surface. Additionally, the binding protein includes a binding region. The N-terminal portion (205) defines the N-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the N-terminus of the binding compound may not be the N-terminus of the binding protein. In one or more embodiments, the N-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the N-terminal portion includes one amino acid that is not a part of a secondary structure. The ability of the N-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids of that portion. In one or more embodiments, the N-terminal portion includes 1 amino acid that defines the N-terminus of the protein. The first beta-strand (1B as in first beta-strand; 260) includes the N-terminus of the binding protein or is directly C-terminal to the N-terminal portion of the binding protein. The first beta-strand has a first beta N-terminus (1B-N; 261) and a first beta C-terminus (1B-C; 262). In one or more embodiments, the first beta-strand defines the N-terminus. In such embodiments, the 1B-N defines the N-terminus of the binding protein. In other embodiments, the first beta- strand does not include the N-terminus of the binding protein. In one or more embodiments, the first beta-strand includes three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the first beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the first beta-strand includes three, four, five, six, seven, eight, nine, or ten amino acid residues. In one or more embodiments, the first beta-strand includes 5 amino acids. The alpha-helix (H; 220) includes a helix N-terminus (H-N; 221 and a helix C-terminus (H-C; 222). The H-N is the most N-terminal amino acid residue of the alpha-helix. The H-C is the most C-terminal amino acid residue of the alpha-helix. In one or more embodiments, the alpha-helix includes 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acids residues. In one or more embodiments, the alpha-helix includes 20 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, 6 or fewer, or 5 or fewer amino acid residues. In one or more embodiments, the alpha-helix includes 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the alpha-helix includes 13 amino acids. The second beta-strand (2B; 280) includes a second beta N-terminus (2B-N; 281) and a second beta C-terminus (2B-C; 282). The 2B-N is the most N-terminal amino acid residue of the second beta-strand. The 2B-C is the most C-terminal amino acid residue of the second beta- strand. In one or more embodiments, the second beta-strand includes three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the second beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the second beta-strand includes three, four, five, six, seven, eight, nine, or ten amino acid residues. In one or more embodiments, the second beta-strand includes seven amino acids. The third beta-strand (3B; 290) includes a third beta N-terminus (3B-N; 291) and a third beta C-terminus (3B-C; 292). The 3B-N is the most N-terminal amino acid residue of the third beta-strand. The 3B-C is the most C-terminal amino acid residue of the third beta-strand. In one or more embodiments, the third beta-strand includes three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more residues. In one or more embodiments, the third beta-strand includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the third beta-strand includes three, four, five, six, seven, eight, nine, or ten amino acid residues. In one more embodiment, the third beta-strand includes seven amino acids. The first loop (1L; 230) couples the first beta-strand (260) to the alpha-helix (220). The first loop includes a first loop N-terminus (1L-N; 231) and a first loop C-terminus (1L-C; 232). The 1L-N is the most N-terminal amino acid residue of the first loop. The 1L-C is the most C- terminal amino acid residue of the first loop. The 1L-N of the first loop is coupled to the 1B-C of the first beta sheet and the 1L-C is coupled to the H-N of the alpha-helix. In one or more embodiments, the first loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the first loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, or four or fewer amino acid residues. In one or more embodiments, the first loop includes three, four, five, six, seven, eight, nine, or ten amino acid residues. In one or more embodiments, the first loop includes three amino acid residues. The second loop (2L; 240) couples the alpha-helix (220) to the second beta-strand (280). The second loop includes a second loop N-terminus (2L-N; 241) and a first loop C-terminus (2L- C; 242). The 2L-N is the most N-terminal amino acid residue of the second loop. The 2L-C is most C-terminal amino acid residue of the second loop. The 2L-N of the first loop is coupled to the H-C of the alpha-helix and the 2L-C is coupled to the 2B-N of the second beta-strand. In one or more embodiments, the second loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the second loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the second loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. In some embodiments, the second loop includes two amino acid residues. The third loop (3L; 250) couples second beta-strand (280) to the third beta-strand (290). The third loop includes a third loop N-terminus (3L-N; 51) and a third loop C-terminus (3L-C, 252). The 3L-N is the most N-terminal amino acid residue of the third loop. The 3L-C is the most C-terminal amino acid residue of the third loop. The 3L-N of the third loop is coupled to the 2B-C of the second beta-strand and the 3L-C of the third loop is coupled to the 3B-N of the third beta-strand. In one or more embodiments, the third loop includes two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or nine or more amino acid residues. In one or more embodiments, the third loop includes ten or fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer, five or fewer, four or fewer, or three or fewer amino acid residues. In one or more embodiments, the third loop includes two, three, four, five, six, seven, eight, nine, or ten amino acid residues. In one or more embodiments, the third loop includes three amino acid residues. The C-terminal portion (207) defines the C-terminus of the binding protein. In one or more embodiments where the binding protein is fused with a second domain to form a binding compound and / or includes additional amino acids (e.g., a purification tag), the C-terminus of the binding compound may not be the C-terminus of the binding protein. In one or more embodiments, the C-terminal portion includes one, two, or three amino acids that are not a part of a secondary structure. In one or more embodiments, the C-terminal portion includes one amino acid that is not a part of a secondary structure. The ability of the C-terminal portion to be a part of a secondary structure depends at least in part on the identity of the amino acid or amino acids. In one or more embodiments, the 3B-C of the third beta-strand defines the C-terminus. Specific amino acid residue locations within the first beta-strand, the first loop, the alpha- helix, the second loop, the second beta-strand, the third loop, and the third beta-strand can be denoted by counting the amino acid residues from the N-terminal or C-terminal amino acid residue of a specified motif. When counting residue numbers from the N-terminal amino acid residue of a specified motif, the residue may be identified as x-N(1+y) where x identifies the motif (1B, H, 1L, 2B, 2L, 2B, 3L, and 3B) and y is the residue number counting from x-N where the residue number of x-N is 1. For example, 1B-N(2) is the second amino acid residue in the first beta-strand. When counting residue numbers from the C-terminal amino acid residue of a specified motif, the residue may be identified as x-C(-1-y) where x identifies the motif (1B, H, 1L, 2B, 2L, 2B, 3L, and 3B) and y is the residue number counting from x-C where the residue number of x-C is -1. For example, 1B-C(-2) is the second to last amino acid residue of the first beta-strand. The binding protein includes a first solvent-exposed surface, a second solvent-exposed surface, and a third solvent-exposed surface. A solvent-exposed surface is a three dimensional region of the protein where at least the side chains of the amino acid residues are projecting into solvent; that is, away from interacting with other residues of the protein such that they are free to interact with a target. The binding protein also includes a binding region that includes at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, or at least a portion of the third solvent-exposed surface. As used herein, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence is structurally similar to the potential sequence. For example, the binding region refers to the specific amino acids of a parental protein that can be varied to engineer protein binding to a target while the rest of the binding protein sequence has 70% or greater, 75% or greater, 80% or greater, 85% or greater, 90% or greater, 95% or greater, or 100% sequence identity or sequence similarity to the parental sequence. Not all amino acids located in the binding region need to engage in binding interactions with the binding target. The binding region can be thought of and referred to as the variable region or paratope. The first solvent-exposed surface includes at least a portion of the beta sheet. In one or more embodiments, the first solvent-exposed surface includes at least a portion of the first beta- strand, second beta-strand, third beta-strand, or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes the N-terminal region, a portion of the first loop, a portion of the second loop, a portion of the third loop, or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid reside. In one or more embodiments, the first solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 9 amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 8 amino acid residues. In one or more embodiments, the first solvent-exposed surface includes 7 amino acid residues. In one or more embodiments, the first solvent-exposed surface includes the N-terminal amino acid; 1, 2, 3, 4, or 5 amino acid residues of the first beta-strand; 1, 2, 3, 4, or 5, amino acid residues of the second loop; 1, 2, 3, 4, or 5 amino acid residues of the second beta-strand; 1, 2, 3, 4, or 5 amino acid residues of the third loop; 1, 2, 3, 4, or 5 amino acid residues of the third beta- strand; the C-terminal amino acid; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes: 1a) the N-terminal amino acid residue of the binding protein; 1b) two amino acid residues of the first beta-strand; 1c) four amino acid residues of the second beta-strand; 1d) three amino acid residues of the second beta-strand; 1e) four amino acids of the third beta-strand; 1f) three amino acids of the third beta-strand; or any combination of 1a through 1f. In one or more embodiments, the first solvent-exposed surface includes 1a, 1b, 1c, and 1e. In one or more embodiments, the first solvent-exposed surface includes 1a, 1b, 1d, and 1f. In one or more embodiments, the first solvent-exposed surface includes 1b, 1d, and 1f. In one or more embodiments, the first solvent-exposed surface includes 1a, 1b, and 1f. In one or more embodiments, the first solvent-exposed surface includes 1a, 1b, and 1c. In one or more embodiments, the first solvent-exposed surface includes 1c and 1e. In one or more embodiments, the first solvent-exposed surface includes: 1g) the N-terminal amino acid of the binding protein; 1h) the 1B-N(2) and 1B-N(4) residues of the first beta-strand; 1i) the 2B-N(1), 2B-N(3), 2B-N(5), and 2B-N(7) of the second beta-strand; 1j) the 2B-N(3), 2B-N(5), and 2B-N(7) of the second beta-strand; 1k) the 2B-N(1), 2B-N(3), and 2B-N(5), of the second beta-strand; 1l) the 3B-N(1), 3B-N(3), 3B-N(5), and 3B-N(7) of the third beta-strand; 1m) the 3B-N(3), 3B-N(5), and 3B-N(7) of the third beta-strand; 1n) the 3B-N(1), 3B-N(3), and 3B-N(5), of the third beta-strand; or any combination thereof. In one or more embodiments, the first solvent-exposed surface includes 1g, 1h, 1i, and 1l. In one or more embodiments, the first solvent-exposed surface includes 1g, 1k, and 1m. In one or more embodiments, the first solvent-exposed surface includes 1h, 1j, and 1l. In one or more embodiments, the first solvent-exposed surface includes 1g, 1h, and 1l. In one or more embodiments, the first solvent-exposed surface includes 1g, 1h, and 1i. In one or more embodiments, the first solvent-exposed surface includes 1i and 1l. In one or more embodiments, the binding region includes at least a portion of the first solvent-exposed surface. In one or more embodiments, the binding region include any combination of 1a through 1f or 1g through 1n such as those described herein. The second solvent-exposed surface includes at least a portion of the alpha-helix. In one or more embodiments, the second solvent-exposed portion further includes a portion of the first loop, a portion of the second loop, or both. In one or more embodiments, the second solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid reside. In one or more embodiments, the second solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the second solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 amino acid residues of the alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the second loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes: 2a) one amino acid residue of the first loop; 2b) eight amino acid residues of the alpha-helix; 2c) one amino acid residue of the second loop or both. In one or more embodiments, the second solvent-exposed surface includes 2a and 2b. In one or more embodiments, the second solvent-exposed surface includes 2b. In one or more embodiments, the second solvent-exposed surface includes 2b and 2c. In one or more embodiments, the second solvent-exposed surface includes: 2d) the L1-C(-1) residue of the first loop; 2e) the H-N(1), H-N(2), H-N(4), H-N(5), H-N(8), H-N(9), H-N(12), and H-N(13) residues of the alpha-helix; 2f) the 2L-N(1) residue of the second loop; or any combination thereof. In one or more embodiments, the second solvent-exposed surface includes 2d and 2e. In one or more embodiments, the second solvent-exposed surface area includes 2d, 2e, and 2f. In one or more embodiments, the second solvent-exposed surface area includes 2e and 2f. In one or more embodiments, the binding region includes at least a portion of the second solvent-exposed surface. In one or more embodiments, the binding region include any combination of 2a through 2c or 2d through 2f such as those disclosed herein. The third solvent-exposed surface includes at least a portion of the first loop and at least a portion of the third loop. In one or more embodiments, the third solvent-exposed surface includes at least a portion of the alpha-helix. In one or more embodiments, the third solvent-exposed surface includes 5 or more, 6 or more 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, 14 or more, 15 or more, 16 or more, 17 or more, 18 or more, or 19 or more amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 20 or fewer, 19 or fewer, 18 or fewer, 17 or fewer, 16 or fewer, 15 or fewer, 14 or fewer, 13 or fewer, 12 or fewer, 11 or fewer, 10 or fewer, 9 or fewer, 8 or fewer, 7 or fewer, or 6 or fewer amino acid reside. In one or more embodiments, the third solvent-exposed surface includes 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 amino acid residues. In one or more embodiments, the third solvent-exposed surface includes 1, 2, 3, 4, or 5 amino acid residues of the first loop; 1, 2, 3, 4, or 5, amino acid residues of the alpha-helix; 1, 2, 3, 4, or 5 amino acid residues of the third loop; 1, 2, 3, 4, or 5 amino acid residues of the second beta-strand; 1, 2, 3, 4, or 5 amino acid residues of the third beta-strand; or any combination thereof. In one or more embodiments, the third solvent-exposed surface includes: 3a) three residues of the first loop; 3b) one amino acid residue of the alpha-helix; 3c) two amino acids residues of the second beta-sheet; 3d) two amino acid residues of the third loop; 3e) one amino acid residue of the third beta-strand; or any combination thereof. In one or more embodiments, the third solvent-exposed region includes 3a, 3b, 3c, 3d, and 3e. In one or more embodiments, the third solvent-exposed region includes 3a and 3d. In one or more embodiments, the third solvent-exposed surface includes: 3f) the L1-N(1), L2-N(2), and L2-N(3) residues of the first loop; 3g) the H-N(1) residue of the alpha-helix; 3h) the B2-C(-1) residue of the second beta-strand; 3i) the B2-C(-1) and B2-C(-2) residues of the second beta-strand; 3j) the L3-N(1) and L3-N(2) residues of the third loop; or any combination of 3d-3h. In one or more embodiments, the third solvent-exposed surface includes 3f, 3g, 3i, and 3j. In one or more embodiments, the third solvent-exposed surface includes 3f, 3g, 3h, and 3j. In one or more embodiments, the binding region includes at least a portion of the third solvent-exposed surface. In one or more embodiments, the binding region include any combination of 3a through 3e or 3f through 3j, such as those described herein. Table 11 shows a table of a 40 amino acid binding protein; the residue numbers of the first beta-strand (B1), the first loop (L1), the alpha-helix (H), the second loop (2L), the second beta-strand (2B), the third loop (3L), and the third beta-strand (3B); the residue numbers of the first solvent-exposed surface (SES1), the second solvent-exposed surface (SES2), and the third solvent-exposed surface (SES3); as well as 8 binding regions (BR1-BR8). The binding protein may have 40 amino acids following the secondary structure residue layout of Table 11 and may have one of the solvent-exposed surfaces and / or binding regions of Table 11. Table 12 shows the binding residue numbers in reference to the secondary structure motifs for BR1 through BR7.

[0007]

[0008] In one or more embodiments, the binding proteins can be derived from the parental proteins (also called framework proteins) of SEQ ID NO:107 (Framework 1, FW1, FW 1), SEQ ID NO:108 (Framework 2, FW2, FW 2), SEQ ID NO:109 (Framework 3, FW3, FW 3), or SEQ ID NO:110 (Framework 4, FW4, FW 4) (See Table 13 for the sequences). SEQ ID NOs:107-110 are computationally designed hyperstable scaffolds designed by Rocklin et al. (Rocklin, G. J., Chidyausiku, T. M., Goreshnik, I., Ford, A., Houliston, S., Lemak, A., Carter, L., Ravichandran, R., Mulligan, V. K., Chevalier, A., Arrowsmith, C. H. & Baker, D. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ).357, 168–175 (2017)).^These proteins were designed to fold into the βαββ topology, not necessarily to tolerate diversification or enable selective binding to a target. SEQ ID NOs:107-110 are 40 amino acid proteins following the secondary structure layout of Table 11. As such, a binding protein of the present disclosure may be derived from any one of parental SEQ ID NOs:107-110 where the amino acid residues of any one of binding regions 1-8 (Table 11 or 12) are varied. In one or more embodiments, the binding protein is a sequence that has 70% or greater, 75% or greater, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of SEQ ID NO:111, SEQ ID NO:112, SEQ ID NO:113, SEQ ID NO:114, SEQ ID NO: 115, SEQ ID NO:116, SEQ ID NO:117, SEQ ID NO:118, SEQ ID NO:119, SEQ ID NO:120, SEQ ID NO:122, SEQ ID NO:123, SEQ ID NO:124, SEQ ID NO:125, SEQ ID NO:126, SEQ ID NO:127, SEQ ID NO:128, SEQ ID NO:129, SEQ ID NO:130, SEQ ID NO:131, SEQ ID NO:132, SEQ ID NO:133, SEQ ID NO:134, SEQ ID NO:134, SEQ ID NO:136, SEQ ID NO:136, SEQ ID NO:137, SEQ ID NO:138, SEQ ID NO:139, SEQ ID NO:140, SEQ ID NO:141, or SEQ ID NO:142 (see Table 14 where each X is independently any amino acid). In SEQ ID NOs:111 – 142, X represents the binding region. Positions that have an X can be varied to develop binding to one or more targets. Table 14 shows the sequences of SEQ ID NOs:111-142. SEQ ID Nos.111-146 are 40 amino acid binding proteins that follow the same secondary structure layout as shown in Table 11. In Table 14, FW1 indicates the sequence was derived from parental sequence SEQ ID NO:107. In Table 14, FW2 indicates the sequence was derived from parental sequence SEQ ID NO:108. In Table 14, FW3 indicates the sequence was derived from parental sequence SEQ ID NO:109. In Table 14, FW4 indicates the sequence was derived from parental sequence SEQ ID NO:110.

[0009] The binding proteins of the present disclosure bind to a target. The target may be a protein such as an enzyme, a transporter protein, a transmembrane protein, a receptor, or a structural protein. In one or more embodiments, the target is an intracellular target. In other embodiments, the target is an extracellular target. For example, in one or more embodiments, the target is a protein that overexpressed by diseased cells and / or located on the surface of diseased cells. In one or more embodiments, the binding protein acts as an agonist (upregulates one or more functions of the target) or an antagonist (at least partially inhibits one or more functions of the target) to the target protein. In other embodiments, the binding protein simply recognizes the target protein. In some such embodiments, the binding protein or a binding compound containing the same can be used for imaging. The binding protein may bind to the target with a variety of dissociation constants (Kdor KD). In one or more embodiments, the binding protein binds a target with a Kdof 1 femtomolar (fM) or greater, 100 fM or greater, 500 fM or greater, 750 fM or greater, 1 picomolar (pM) or greater, 100 pM or grater, 500 pM or greater, 750 pM or greater, 1 nanomolar (nM) or greater, 50 nM or greater, 100 nM or greater, 500 nM or greater, or 750 nM or greater. In one or more embodiments, the binding protein binds a target with a Kdof 1 micromolar (μM) or less, 750 nM or less, 500 nM or less, 100 nM or less, 50 nM or less, 1 nM or less, 750 pM or less, 500 pM or less, 100 pM or less, 500 fM or less, or 100 fM or less. In one or more embodiments, the binding protein binds to a target with a Kdof 1 fM to 1 μM, 1 fM to 750 nM, 1 fM to 500 nM, 1 fM to 100 nM, 1 fM to 1 nM, 1fM to 750 pM, 1 fM to 500 pM, 1 fM to 100 pM, 1 fM to 1 pM, 1 fM to 750 fM, 1 fM to 500 fM, 1 fM to 100 fM, 100 fM to 1 μM, 100 fM to 750 nM, 100 fM to 500 nM, 100 fM to 100 nM, 100 fM to 1 nM, 100 fM to 750 pM, 100 fM to 500 pM, 100 fM to 100 pM, 100 fM to 1 pM, 100 fM to 500 fM, 100 fM to 750 fM, 500 fM to 1 μM, 500 fM to 750 nM, 500 fM to 500 nM, 500 fM to 100 nM, 500 fM to 1 nM, 500 fM to 750 pM, 500 fM to 500 pM, 500 fM to 100 pM, 500 fM to 1 pM,1 pM to 1 μM, 1 pM to 750 nM, 1 pM to 500 nM, 1 pM to 100 nM, 1 pM to 1 nM, 1 pM to 750 pM, 1 pM to 500 pM, 1 pM to 100 pM, 100 pM to 1 μM, 100 pM to 750 nM, 100 pM to 500 nM, 100 pM to 100 nM, 100 pM to 1 nM, 100 pM to 750 pM, 100 pM to 500 pM, 500 pM to 1 μM, 500 pM to 750 nM, 500 pM to 500 nM, 500 pM to 100 nM, 500 pM to 1 nM, 500 pM to 750 pM, 750 pM to 1 μM, 750 pM to 750 nM, 750 pM to 500 nM, 750 pM to 100 nM, 750 pM to 1 nM, 1 nM to 1 μM, 1 nM to 750 nM, 1 nM to 500 nM, 1 nM to 100 nM, 100 nM to 1 μM, 100 nM to 750 nM, 100 nM to 500 nM, 500 nM to 1 μM, 500 nM to 750 nM, or 750 nM to 1 μM. In one or more embodiments, the target is B7-H3. B7 Homolog 3 (B7-H3), also known as cluster of differentiation 276 (CD276), is a human protein encoded by the CD276 gene. The B7- H3 protein is a 316 amino acid-long type I transmembrane protein existing in two isoforms determined by its extracellular domain. B7-H3 mRNA is expressed in most normal tissues. In contrast, B7-H3 protein has a very limited expression on normal tissues because of its post- transcriptional regulation by microRNAs. In normal tissues, B7-H3 has a predominantly inhibitory role in adaptive immunity, suppressing T cell activation and proliferation. As such, B7-H3 is an important immune checkpoint inhibitor of T-cell function, is a tumor vasculature biomarker, and is overexpressed in a variety of cancers, including clear cell renal cell carcinoma, cutaneous melanoma, diffuse intrinsic pontine glioma, hypopharyngeal squamous cell carcinoma, non-small cell lung cancer, ovarian cancer, prostate cancer, and pancreatic cancer. The expression of B7-H3 is associated with tumor growth and metastasis and may ultimately lead to poor clinical prognosis. In one or more embodiments, the binding protein binds B7-H3, PSMA, CD22, IRA, IgG, or any combination thereof. Table 15 shows examples of sequences that bind to B7-H3, PSMA, CD22, IRA, and IgG. In Table 15, the ID indicates the target the binding protein binds to.

[0010] In one or more embodiments, where the binding protein binds B7-H3, the binding protein has an amino acid sequence that is 70% to 100%, 75% to 100%, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of B7-H3# 1 (SEQ ID NO:143), B7-H3# 2 (SEQ ID NO:144), B7-H3# 3 (SEQ ID NO:145), or B7-H3#4 (SEQ ID NO:146). B7-H3#1 was derived from the parental protein of framework 2 (SEQ ID NO:108). B7-H3#2 and B7-H3# 4 were derived from the parental protein of framework 2 (SEQ ID NO:107). B7-H3#2 was derived from the parental protein of framework 4 (SEQ ID NO:110). B7-H3#2 was derived from the parental protein of framework 1 (SEQ ID NO:107). In one or more embodiments, the target is PSMA. Prostate-specific membrane antigen (PSMA) is a membrane protein that is over expressed in prostate cancer cells. In one or more embodiments, where the binder protein binds PSMA, the binder protein has an amino acid sequence that is 70% to 100%, 75% to 100%, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of PSMA# 1 (SEQ ID NO:147), PSMA# 2 (SEQ ID NO:148), or PSMA# 3 (SEQ ID NO:149). PSMA# 1 was derived from the parental protein of framework 1 (SEQ ID NO:107). PSMA# 2 and PMSA# 3 were derived from the parental protein of framework 4 (SEQ ID NO:110). In one or more embodiments, the target is CD22. Cluster differentiation-22 (CD22) is a membrane protein present on the surface of B-cells that helps regulate the immune system. In one or more embodiments, where the binder protein binds CD22, the binder protein has an amino acid sequence that is 70% to 100%, 75% to 100%, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of CD22 #1 (SEQ ID NO:150) or CD22 #2 (SEQ ID NO:152). CD22#1 and CD22#2 were derived from the parental protein of framework 2 (SEQ ID NO:108). In one or more embodiments, the target is IgG. In one or more embodiments, where the binder protein binds CD22, the binder protein has an amino acid sequence that is 70% to 100%, 75% to 100%, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of IgG #1 (SEQ ID NO:181), IgG #2 (SEQ ID NO:182), or IgG #3 (SEQ ID NO:183). In one or more embodiments, the target insulin receptor A (IRA). IRA is a transmembrane protein that helps regulation of glucose homeostasis. In one or more embodiments, where the binder protein binds IRA, the binder protein has an amino acid sequence that is 70% to 100%, 75% to 100%, 85% to 100%, 90% to 100%, 95% to 100%, or 97% to 100% sequence identity or sequence similarity to any one of IRA 2-1 through IRA 2-23 (SEQ ID NOs:152-174); IRA 1-16 through IRA 1-20 (SEQ ID NOs:175-179); or IRA 1-82 (SEQ ID NO:180). IRA-2-16 (SEQ ID NO:167) and IRA 2-19 (SEQ ID NO:170) were derived from the parental protein of framework 1 (SEQ ID NO:107). IRA-2-1 through IRA 2-15, IRA 2-15 through IRA 2-18, IRA 2-20 through IRA 2-23, IRA 1-16 through IRA 1-20, and IRA 1-82 were derived from the parental protein of framework 2 (SEQ ID NO:108). The binding of binding proteins IRA 2-1 through IRA 2-23, IRA 1-16 through IRA 1-20, and IRA 1-82 to IRA and IRB (insulin receptor B, an isoform of IRA) was measured at multiple concentrations (5,50, 100, and 500 nM). FIG. 99 is a plot showing the average of z scores (of A binding signal) calculated for each of those concentrations (x-axis) compared to the average z signal of a normalized IRA signal divided by the IRB signal (y-axis). Experimental binding proteins that have or are derived from proteins having three beta- strands and one alpha-helix Example 1 describes the experimental methods used to produce and test the binding proteins that have and / or are derived from proteins having a three-helix bundle and binding proteins that have and / or are derived from proteins having a having four beta-strands and one alpha-helix. Four of the most stable babb framework sequences (FW; FW1 = SEQ ID NO:107; FW2= SEQ ID NO:108, FW3 = SEQ ID NO:109; and FW4 = SEQ ID NO:110) from Rocklin et al. (Rocklin, G. J., Chidyausiku, T. M., Goreshnik, I., Ford, A., Houliston, S., Lemak, A., Carter, L., Ravichandran, R., Mulligan, V. K., Chevalier, A., Arrowsmith, C. H. & Baker, D. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ). 357, 168–175 (2017)), were selected as lead molecules to build binding protein scaffold libraries (FIG.56 and FIG.57). The frameworks exhibit only 30% sequence identity across all four frameworks and 50-55% sequence identity between any two frameworks yet maintain structural similarity (average root-mean squared difference of 0.8 Å, FIG.58) thereby providing a diverse set of chemical contexts within this topology. Various secondary structures have functioned as engineered ligand paratopes in other scaffolds, albeit with differential performance. Moreover, the relative mutational tolerance and binding capacity of different regions of these synthetic scaffolds are not known. Thus, the b-sheet surface, a-helical surface, and a pair of adjacent solvent-exposed loops were individually diversified (e.g., binding sites; FIG.56 and FIG.57) and the evolvability and developability of the resultant collection of variants was assessed. The sequences and variable regions of the libraries are shown in Table 11. The a-helix and loops provided nine surface sites, which is a reasonable paratope size (i.e., binding region) to engineer novel binding functionality. The full b-sheet surface provides 11 sites. For a more even comparison across structures and to avoid destabilizing over-diversification, sublibraries with partial diversification of the b-sheet surface focused on either two of the three strands or a reduced ‘length’ of the sheet were also tested (FIG.56 and FIG.57). Diversified genes (FIG.78A, 78B, 78C, 78D) were assembled and transformed into a yeast display system, as genetic fusions to the C-terminus of Aga2p with flanking epitope tags, via homologous recombination with a pCT vector. An average of 3.8×106transformants (range: 1.1×105– 1.7×107) per sublibrary for a total of 1.7×108variants was achieved.93% of transformants had DNA sequences that matched scaffold design, and amino acid frequencies matched design with an average deviation of 0.8% (FIG.79). To assess evolvability of each framework and paratope / binding region (secondary structure, size, location, and sequence), all the sublibraries (see Table 14 or the sequences) were pooled into a single library and the single library was sorted the for binders to seven targets with potential clinical utility: PSMA, CD22, natural killer cell p46-related protein (NKp46; also known as NCR1), insulin receptor isoform A (IRA), tumor endothelial marker 8 (Tem8; also known as ATR1), immunoglobulin G (IgG), and B7 homolog 3 (B7-H3; also known as CD276). These target proteins have varied structure (FIG.81) and thereby test the scaffolds’ abilities to bind to a wide variety of protein structures. Populations of variants exhibiting specific binding to nM concentrations of target were enriched for all targets following magnetic-activated cell sorting (MACS) and fluorescence-activated cell sorting (FACS) without the need for affinity maturation (FIG.82). Binding populations showed minimal binding to multiple non-target proteins at 100 nM (FIG. 82). Deep sequencing of all binding populations revealed the diversity and identity (framework, binding site (paratope) type, size, location, and sequence) of binders. 30,012 unique binders were discovered against 7 targets with the most effective designs yielding an average of 215-772 binders per target. To further assess scaffold functionality, several randomly selected clones to B7-H3, CD22, IgG, and PSMA from the enriched binding pool were tested for affinity, and the best binders were produced and characterized (FIG.59, FIG.60, FIG.61, FIG.62, FIG.63, FIG.9, FIG.80, FIG.81, and FIG.82). The best of the tested clones had high affinity (range: 6 to 33 nM) while several others had more moderate affinity (range: 103 to 122 nM) (FIG.59 and FIG. 83 and FIG.84). Two of the tested CD22 clones had minimal binding at 100 nM and were not tested further. The tested clones also possessed high specificity with minimal binding to several off-target proteins (FIG.60, FIG.85, and FIG.86).^To further assess the specificity and functional binding of these proteins, recombinantly produced B7-H3 binders were tested against mammalian cell expressed B7-H3 and B7-H3 KO cells. B7-H3 binding variants exhibit strong B7-H3 binding at 50 nM and essentially no binding to B7-H3 KO cells at 1000 nM (FIG.105, FIG.106, and FIG.107). Produced proteins had an average Tmof ≥ 78 ºC (range: 54 ºC to ≥ 90 ºC) (FIG.61, FIG.62, FIG.87, FIG.88, FIG.89, and FIG.90) without selecting for stability and an average expression of 1.5 mg / L (range 0.02 to 5.04) (FIG.62) with no codon or protocol optimization. IgG #1 and IgG #2 were codon optimized, and had significantly higher yields. To assess if diversified clones fold comparably to parental frameworks, the structures for the 12 characterized clones as well as 48 other binding clones selected with a range of stabilities and targets were calculated via AlphaFold (Jumper, J., Evans, R., Pritzel, A., Green, T., Figurnov, M., Ronneberger, O., Tunyasuvunakool, K., Bates, R., Žídek, A., Potapenko, A., Bridgland, A., Meyer, C., Kohl, S. A. A., Ballard, A. J., Cowie, A., Romera-Paredes, B., Nikolov, S., Jain, R., Adler, J., Back, T., Petersen, S., Reiman, D., Clancy, E., Zielinski, M., Steinegger, M., Pacholska, M., Berghammer, T., Bodenstein, S., Silver, D., Vinyals, O., Senior, A. W., Kavukcuoglu, K., Kohli, P. & Hassabis, D. Highly accurate protein structure prediction with AlphaFold. Nature 1–11 (2021)). The majority of clones have predicted tertiary structures very similar to the parental frameworks (FIG.63), with an average RMSD of 0.9 Å (FIG.64). B7-H3 #1 and 4 are both predicted to have an unfolded third sheet. A caveat is that these structures are computationally predicted rather than experimentally measured. To account for this, circular dichroism was used to determine secondary structure of proteins (FIG.61, FIG.80, FIG.87, FIG.88, FIG 89, and FIG.90), and all showed elements of both helical and sheet structure, with many showing similar secondary structures to parents. Inclusion of AS and GS linkers as well as a H6tag may account for some of the differences from parental FWs. Evolvability was measured and compared for each design of framework, paratope structure, and paratope size and location by comparing enrichment of the library in the binding population relative to the unsorted library. babb scaffold evolvability varied over both framework and paratope (FIG.65 and FIG.66). FW1 exhibited the most evolvability across different paratopes while FW4 yielded abundant binders in several paratope designs (FIG.65), including a comparable enrichment of binders with the helix paratope as FW1 (FIG.91). FW2 yielded binders primarily from the sheet paratope, while FW3 was generally less effective except for diversification of eight sites in three sheets (β ABC8; see FIG.92). Evolvability scores calculated using populations after magnetic bead sorting (MACS) showed little difference relative to populations after more stringent FACS sorting (MACS vs 100 nM FACS, R2=0.70; MACS vs 10 nM FACS, R2=0.82). Overall, framework has a much larger effect on evolvability than paratope choice. Diversification of three adjacent sheets nominally provides the most effective evolutionary performance (FIG.66), however, for FW4, the helix paratope is most effective. Diversification of three sheets was nominally more effective than diversification of two sheets for all frameworks (FIG.91). ABC8 and ABC11 are nominally the most performant three-sheet libraries, which may indicate a benefit of diversification of sites at the C-terminus of strand B and the N-terminus of strand C (FIG.56 and FIG.92). AC7 is the nominally least effective two- sheet library, which potentially indicates the second b-sheet as being important to diversify for evolvability (FIG.92). The helical paratope is moderately effective for the two most evolvable frameworks, with low effectiveness for the two least evolvable (FIG.36). The loop paratope is comparably the least effective (FIG.91) yet still functional as 2,274 binders were identified via loop diversification albeit at a much lower frequency (and / or binding strength) than from other paratopes. One reason that paratope choice seems to play less of a role than framework in determining evolvability, is that different targets seem to prefer different paratopes for binding (FIG.70). Along with primary function, such as binding, developability is also requisite for protein utility. We evaluated multiple aspects of developability via two assays: proteolytic and thermal stability measured via a yeast display protease assay; and solubility and expression measured via a bacterial split-GFP assay (Golinski, A. W., Mischler, K. M., Laxminarayan, S., Neurock, N. L., Fossing, M., Pichman, H., Martiniani, S. & Hackel, B. J. High-throughput developability assays enable library-scale identification of producible protein scaffold variants. Proc. Natl. Acad. Sci. U. S. A.118, e2026658118 (2021)). Stability evaluation was generalized by running the protease assay with two different proteases (proteinase K and thermolysin) and running each protease at two different temperatures (37 ºC and 55 ºC for proteinase K, 55 ºC and 75 ºC for thermolysin). Moderate difference was observed between protease treatments (R2=0.54), indicating the importance of testing resistance to multiple proteases. Protease resistance between varied temperatures showed high correlation (proteinase K, R2=0.90, thermolysin, R2=0.87). Unlike evolvability, developability varies more strongly with paratope type than framework (FIG.68 and FIG.69). FW1 variants exhibit the most stability to proteinase K (FIG. 68). FW3 exhibits slightly lower soluble expression than the other parental frameworks. From a paratope perspective, b-sheet diversity yields high protease stability to both proteinase K and thermolysin (FIG.14). Helix paratopes generally exhibit comparably high thermolysin stability, but only FW1 and FW2 exhibit proteinase K stability. Conversely, loop paratopes exhibit low resistance to proteolysis. In addition to their superior protease resistance, b-sheet paratope variants also exhibit the highest soluble expression. While b-sheet paratope variants are generally the most developable, diversification of different sites on the sheets results in varied developability. The 3-strand paratope variants exhibit protease stability and soluble expression as good or better than various 2-strand paratopes (FIG.70). Conversely to evolvability (FIG.65), an intermediate number of diversified sites (9 vs.8 or 11) excluding the C-terminus of strand B and the N-terminus of strand C is optimal for protease stability and soluble expression. Diversifying sheet B without diversifying both sheets A and C also is destabilizing. Three-sheet, 11-site diversification is very detrimental to bacterial expression. These developability analyses were based on library prevalence in the most stable populations. Alternate analysis of the distribution of all stabilities across the library generally aligned in indicating the most performant designs (FIG.83 and FIG.94). In several cases, however, these two stability scores do not correlate. While loop libraries have very few highly stable clones (FIG.69), they have comparable average stabilities to helix or sheet libraries (FIG 93 and FIG.94). While many FW2 and 3 β3designs have many highly stable clones, they have much lower average stabilities to other libraries (FIG.70, FIG.93, and FIG.94). While stability varies across paratopes and frameworks for the libraries, binding variants generally exhibit higher stability than non-binders (FIG.71 and FIG.72 especially against proteinase K. βαββ binders are generally more resistant to proteinase K than to thermolysin, and FW1 and FW4 are generally more resistant to proteinase K than FW2 or FW3. FW1 binders on average exhibit lower (albeit equal to other FWs) resistance to thermolysin than the naïve library does (FIG.72). In clonal evolution, stability and function may trade off; thus, high parental stability is beneficial to stability to enable structural tolerance upon mutation for new or improved function. Yet, in the current context of library discovery, the trade-off is not strongly observed. Rather, variants that maintain structural integrity (as assessed via protease resistant stability) are more functional. The observation may result from reduced entropic cost of binding for rigid structures or an alternative mechanism. In either case, the results indicate that parental hyperstability may be insufficient for evolvability, but with appropriate diversification, novel function can be achieved with (and perhaps because of) maintained stability. Developability and evolvability were examined simultaneously to identify libraries that exhibited high scores in both metrics (FIG.73, FIG.74, and FIG.75). The libraries with three b- strands diversified from FW1 exhibit the best performance. FW1 β ABC8 emerged as the most promising scaffold. Other designs are also effective albeit with moderate shortcomings revealed by analysis of the components of evolvability and developability (FIG.73 and FIG.74). FW1 β ABC11 is evolvable and stable but exhibits moderate recombinant expression. FW1 β ABC9 is highly developable but yielded few binders for Tem8 or B7-H3. Diversification of two β-strands in FW1 is reasonably effective albeit with poor thermolysin stability. The α-helix library of FW1 is stable and yields binders to several targets but exhibits moderate expression and is less effective against several other targets. A library of 11 sites in three β-strands in FW4 is also stable and moderately evolvable albeit with poor expression. Overall, nine libraries had both developability and evolvability scores above one. Many other highly developable libraries had low evolvability scores, whereas no libraries had low developability but high evolvability. While some libraries were generally more evolvable than others, few libraries were enriched in the binding pool relative to the naïve library for all campaigns. The evolvability of the three paratope structures depends upon the target of choice, potentially due to shape differences in the target epitopes (i.e., binding sites on the target). Against three targets (B7-H3, IgG, and Tem8), helical libraries show strong evolvability and loops show the lowest evolvability (FIG.67). Against three other targets (NKp46, IRA, PSMA), sheets display strong evolvability, and helix libraries show lower evolvability than loop libraries. Against CD22, all three paratope types have similar evolvability scores. While the mechanism behind these preferences is not fully elucidated, the results indicate that binder discovery against new targets with these βαββ proteins would benefit from a mixture of paratope structures. This trend aligns with a previous study that showed that scaffolds with different paratope surfaces have performed better at binding different types of targets due to their shape. To elucidate how paratope sequence effects performance, amino acid enrichment of sheet libraries in the binding and developable populations relative to the unsorted library were calculated for each framework at each diversified site. Multiple sites exhibit substantial selective amino acid enrichment in binding clones (FIG.76). For example, sites 1, 3, 31, and 38 are enriched in select aromatic amino acids; sites 3 and 31 also enrich medium hydrophobic amino acids. Conversely, sites 5 and 29 – and to a lesser extent site 27 and 34 – enrich negatively charged amino acids. For sheet libraries, amino acid enrichment trends are generally consistent between FW1, FW2, and FW4, but diverge for FW3, which was notably the least evolvable framework. As for developability, negative charges are generally unfavorable for protease stability but are favorable for GFP expression (FIG.77). Cysteine is enriched in the most stable clones, although not in β-strand C. Nonpolar I, L, and V as well as aromatic residues are generally favored. Proline at select sites hinders protease resistance in sheet paratopes but aids soluble expression of variants at sites 38 and 34 (FIG.78). Amino acid enrichment data for the most promising scaffolds could be combined to create even more promising second-generation libraries. For FW1 β ABC8, binding clones tend to prefer negatively charged amino acids at select sites, and non-polar or aromatic residues at remaining sites (FIG.95). For protease resistance, negatively charged amino acids are unfavorable, and nonpolar resides are generally favorable. While these enrichments (and enrichment for split-GFP) do not fully align, they can be combined to develop an improved second-generation library. Several sites are either enriched or depleted for all three and can be increased or decreased in a combined library. Otherwise, the select sites that have high negative charge enrichment in the binder pool can be preferentially designed for negative charge but the other negatively charged residues can be lessened in future designs to increase stability. Amino acid enrichment values were also calculated for 1-α (FIG.96) due to the target preference for different paratopes.1-α (FIG.96) is enriched in non-polar / aromatic / cysteine for thermolysin resistance, and cysteine / polar / positively charged for proteinase K resistance, whereas binder enrichment generally favors positively charged or non-polar for helices. Four computationally designed hyperstable βαββ mini-proteins (40 amino acids) were evaluated as scaffolds for binding protein engineering by diversifying various paratopes. Across 43 designs of systematically varied framework sequence, paratope structure, location, and size, the βαββ proteins exhibit a range of performance, with multiple effective scaffolds yielding discovery of numerous binders against seven different targets. Many of these scaffolds were also developable, with sheet libraries generally being the most developable. FW1 three-strand diversified libraries emerged as promising scaffolds due to their high developability and evolvability. Affinities of 6 - 122 nM were achieved in direct selection from a modest library size without affinity maturation, with only a single round of FACS, and with tested clones chosen randomly from the FACS pools. Directed evolution, increased FACS stringency, and / or selecting clones based on both frequency and enrichment would likely result in even higher affinity clones. Leading scaffolds and many of the tested binders have high developability. The initial frameworks and most of the evolved clones (100% of the 12 of characterized clones, 96% of all binders) lack disulfide bonds yet exhibit high stability. Many of the engineered proteins maintain the high stability of the parent despite mutating 7-11 sites of the 40-amino acid protein, with 6 of 9 variants having a Tm≥ 80 ºC and not exhibiting a denatured plateau via CD as the temperature reached 95 ºC. The proteins produced in this study have only moderate yield in unoptimized shake flask culture (average of 1.5 mg / L produced), however, many were not codon optimized for bacteria. Most notably, B7H3 #1 contains an AGG codon for R while B7H3 #4 has an AGG and a CGA codon for R. Codon design, fermentation optimization, or even solid-phase synthesis could be pursued to enhance productivity. In general, loops were the least effective paratope tested across frameworks for both developability and evolvability. The loops in question, however, are very short and lack the length and flexibility present in a traditional loop paratope. Extending the loops to resemble the lengths seen in other scaffolds may make the βαββ loop paratope more viable. Framework 1 was the most evolvable framework and was the source of the three most evolvable and developable libraries. This is consistent with previous data showing that highly stable proteins are a strong starting point for engineering new function. However, all 43 designed protein libraries were based upon highly stable proteins (Tms ≥85 ºC), and many were lacking in either evolvability or developability, thereby challenging the prediction of whether new βαββ FWs similarly designed to be hyperstable would also be good scaffolds. Modifications of Binding Proteins In one or more embodiments, a binding protein of the present disclosure may include additional sequences, such as, for example, amino acids appended to the C-terminal or N- terminal end of the binding protein. Such modifications can, for example, facilitate purification by trapping on columns, the use of antibodies, or facilitate recovery when expressed recombinantly in a microbe. Such tags include, for example, a histidine-rich tag that allows purification of proteins on nickel columns and / or a leader sequence that can traffic a recombinantly-expressed binding proteins to the membrane of the cell in which it is recombinantly expressed. Such gene modification techniques and suitable additional sequences are well known in the molecular biology arts. In one or more embodiments, the C-terminal and / or N-terminal modification may be cleaved from the binding protein before being incorporated into, for example, a pharmaceutical composition. In other embodiments, retaining a C-terminal or N-terminal modification may be desired for a given application—e.g., to facilitate immobilization to a substrate. In one or more embodiments, a binding protein described herein also may include N- terminal or C-terminal functionalities other than a carboxylic acid or free amine. For example, the C-terminus, N-terminus, or both, of an affibody may be acylated, for example, acetylated. In one or more embodiments, the functionality may include a polyol (e.g., polyethylene glycol). In one or more embodiments, a binding protein described herein may include post- translational modifications on one or more amino acids. Examples of post-translational modifications include, but are not limited to, acetylation, methylation, glycosylation, phosphorylation, prenylation, sulfonation, palmitoylation, hydroxylation, nitration, myristoylation, formylation, or citrullination. Post-translational modifications may be incorporated specifically or non-specifically through methods known in the biological arts. Methods of Making Binding Proteins In one or more embodiments, a binding protein may be produced recombinantly in a suitable host cell and then purified. Methods for recombinant production and purification of proteins are well known in the art. In one or more embodiments, the binding proteins of the present disclosure may be produced using solid phase peptide synthesis. In this method of production, the binding protein may be synthesized as one complete polypeptide or in multiple polypeptide fragments that can be joined using native chemical ligation, expressed protein ligation, Staudinger ligation, or Ser / Thr ligation. Methods for solid phase peptide synthesis and ligation techniques are well known in the art. In another aspect, this disclosure describes polynucleotides that encode any of the anti- binding proteins described herein, and the complements of such polynucleotide sequences. Given the amino acid sequence of any binding protein, a person of ordinary skill in the art can determine the full scope of polynucleotides that encode that amino acid sequence using conventional, routine methods. Screening Libraries In another aspect, the present disclosure describes a plurality of screening proteins. The plurality of screening proteins may be called a screening library. The screening proteins are the same as the binding proteins except that the screening proteins may or may not bind to a target with a dissociation constant of 1 μM or less. For example, the screening library may include screening proteins that are binding proteins and screening proteins that do not bind to a target. Each protein of the plurality of screening proteins has 85% to 100%, 90% to 100%, or 95% to 100% sequence identity at all locations except at the binding region. For example, the screening proteins are derived from a parental sequence where one or more amino acid residues of a binding region are diversified. The binding regions of the screening proteins, such as those disclose herein, of the screening proteins may differ from the parental protein by one or more amino acids. The library general includes many screening proteins that are derived from the same parental sequence but have different binding region amino acids. In some cases, the binding regions of the screening proteins may be the same and at least one amino acid in the binding region is different between the screening proteins. The binding regions of the screening proteins are diversified to engineer target binding. In some cases, a library may include two or more screening proteins that have the same sequence. The screening proteins of the present disclosure can be derived from a variety of parental protein (also called framework sequences, frameworks, scaffolds, scaffold sequences, and framework structures). A screening protein derived from a parental protein is a protein that includes the parental protein sequence except at one or more binding region residues (as described herein). As such, the screening proteins of the present disclosure can be described as derived from a parental sequence. For example, a screening protein may be derived from a parental sequence by varying one or more amino acids in the binding region. In one or more embodiments, the screening protein derived from a parental protein may deviate from the secondary structure or tertiary structure of the parental protein. For example, a screening protein derived from a parental protein may have a beta-sheet that includes only two beta-strands whereas the beta-sheet of the parental protein has three beta-strands. In one or more embodiments, the screening proteins may be derived from any parental protein described herein. In one or more embodiments, a screening protein may be any one of SEQ ID NOs:7-30 where X represents a possible site of diversity from the parental sequence (see Table 4 and Table 4 explanation). In one or more embodiments, a screening library includes a plurality of screening proteins of any one of SEQ ID NOs:7-30 where the screening protein sequences differ from each other by at least one amino acid at any one of the binding region residue locations (Xs in SEQ ID NOs:7-30). For example, a screening library may include a plurality of screening proteins of SEQ ID NO:10, where each of the screening proteins differ from each other by at least one amino acid in the binding region. In one or more embodiments, a screening protein may be any one of SEQ ID NOs:73-102 where X represents a possible site of diversity from the parental sequence (see Table 9 and Table 9 explanation). In one or more embodiments, a screening library includes a plurality of screening proteins of any one of SEQ ID NOs: 73-102 where the screening protein sequences differ from each other by at least one amino acid at any one of the binding region residue locations (Xs in SEQ ID NOs: 73-102). For example, a screening library may include a plurality of screening proteins of SEQ ID NO:75, where each of the screening proteins differ from each other by at least one amino acid in the binding region. In one or more embodiments, a screening protein may be any one of SEQ ID NOs:111- 142 where X represents a possible site of diversity from the parental sequence (see Table 14 and Table 14 explanation). In one or more embodiments, a screening library includes a plurality of screening proteins of any one of SEQ ID NOs:111-142where the screening protein sequences differ from each other by at least one amino acid at any one of the binding region residue locations (Xs in SEQ ID NOs: 111-142). For example, a screening library may include a plurality of screening proteins of SEQ ID NO:116, where each of the screening proteins differ from each other by at least one amino acid in the binding region. Screening Methods In another aspect, the present disclosure describes a screening method. The screening method may be used to screen the screening library to find one or more binding proteins. The screening method includes exposing the screening library to a target. The target may be an extracellular target or an intracellular target. The screening library can be a screening library described herein. The screening method further includes sorting the screening library for screening proteins that bind to the target (i.e., binding proteins). Various methods may be used to separate screening proteins that bind to the target from screening proteins that do not bind the target. For example, fluorescence activated cell sorting (FACS) or magnetic activated cell sorting (MACS) may be used to sort the screening library in embodiments where the library is displayed using yeast display or phage display. The screening method further includes determining the amino acid sequence of at least one of the screening proteins bind to the target with a dissociation constant of 1 μM or less. Determining the amino acid sequence may be accomplished by various well known sequencing methods. Binding Compounds In one aspect, this disclosure describes binding compounds that are or include a binding protein of the present disclosure. In addition to the binding protein, in one or more embodiments, the binding compound may include a first functional component operably linked to the binding protein. In one or more embodiments, the first functional component may include a targeting component. In one or more embodiments, the first functional component may include an imaging component. In one or more embodiments, the first functional component may include an enzyme. In one or more embodiments, the first functional component may include a small molecule drug, a pharmacologically active derivative thereof, or an activatable inactive form of a drug (e.g., a prodrug). In one or more embodiments, the first functional component includes a targeting component. In embodiments where the first functional component includes a targeting component, the binding compound may be an immunotherapeutic compound. Immunotherapeutic binding compounds can provide individualized treatment that activates or suppresses the immune system to amplify or diminish an immune response and is developing rapidly for treating various forms of cancer. Immunotherapy for cancer, such as chimeric antigen receptor (CAR)-T cells, CAR-natural killer (NK) cells, PD-1 and PD-L1 inhibitors, aims to help a subject’s immune system fight cancer. In one or more embodiments, the targeting component may bind to and recruit an effector cell to a cell displaying the target of the binding protein. Types of effector cells include, but are not limited to, natural killer (NK) cells, B cells, or T cells. The targeting component may bind to a surface protein displayed on the effector cell. Non-limiting examples of surface proteins displayed on NK cells include, CD16, PD-1, NKp30, NKp40, NKp44, NKp46, NKG2C, or KIRs. Non-limiting examples of surface proteins displayed on B cells include CD4, CD8, or VLA-4. Non-limiting examples of surface proteins displayed on T cells include (LFA)-1, CD2, CD4, or CD8. In one or more embodiments, the targeting component may include an antibody or fragment thereof, an affibody, a peptide, a protein, or a small molecule. In one or more embodiments, the first functional component includes an imaging component. In embodiments where the first functional component includes an imaging component, the binding compound may be used as a diagnostic tool to detect cells and tumors that display the target of the binding protein. The imaging component may be any component that can produce a detectable signal. Exemplary types of imaging components include, but are not limited to a colorimetric label, a fluorescent label, a radioactive label, a magnetic label, or an enzymatic label. Depending on the type of imaging component, various methods may be used to detect the imaging component. Example detection methods include magnetic resonance imaging (MRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), ultrasound, photoacoustic imaging, fluorescence microscopy, total internal reflection fluorescence (TIRF)- microscopy, or stimulated emission depletion (STRED)-nanoscopic. The imaging techniques may be accomplished in vivo or in vitro. In one or more embodiments, the first functional component may include an enzyme. In one or more embodiments, the enzyme may modify one or more of the surface proteins displayed on the cell displaying the target of the binding protein. Examples of enzymes that modifies surface proteins, include but are not limited to, a protease, a lipase, or a sortase such as sortase A. In one or more embodiments, the first functional component may include a small molecule drug. As used herein, the term “drug” is used to collectively refer to a pharmacologically active substance or an activatable inactive form of a pharmacologically active substance (e.g., a prodrug). In embodiments where the first functional component includes a small molecule drug, the binding compound may be a chemotherapeutic compound. In one or more embodiments, the chemotherapeutic binding compound may include one or more radioisotopes. In embodiments where the chemotherapeutic binding compound includes one or more radioisotopes, the binding compound may be used for radioisotope therapy (radionuclide therapy). Examples of suitable isotopes include iodine-131, iridium-192, strontium-89, samarium-153, rhenium-186, boron-10, phosphorus-32, or radium 223. The binding protein may allow for localization of the small molecule drug to cells displaying the target of the binding protein, such as tumor cells, thereby delivering the chemotherapeutic binding compound to a tumor cell that expresses the target. In this way, the chemotherapeutic binding compound may be administered to a subject systematically yet have increased local activity and reduced systemic side effects compared to administering the drug systemically without being a component of a binding compound that includes the binding protein. In one or more embodiments, the binding compound may include additional functional components in addition to the first functional component and the binding protein. For example, the binding compound may include a second functional component, a third functional component, a fourth functional component, a fifth functional component, a sixth functional component, or a seventh functional component. Each functional component may include a binding protein or include an imaging component, an enzyme, a small molecule drug, or a targeting component (all of which are previously described herein), independent of the identity of any other component in the compound. In one or more embodiments where the binding compound includes at least one functional component, the binding protein and the functional component are operably linked. As used herein, the term “operably linked” refers to a direct or indirect covalent linking between the binding protein and any additional functional component or functional components of the compound. Thus, two functional components, or one functional component and the binding protein, that are operably linked may be directly covalently coupled to one another. Conversely, two operably linked functional components, or one functional component operably linked to the binding protein, may be connected by mutual covalent linking to an intervening component (e.g., a flanking sequence or linker). For example, in embodiments where the binding compound includes two functional components, the first functional component and the second functional component may be separately directly linked to the binding protein; or the first functional component may be directly linked to the binding protein and the second functional component directly linked to the first functional component. The binding protein and the first functional component may be operably linked through one or more linkers. The term “linker” as used herein refers to any bond, small molecule, peptide sequence, or other vehicle that physically links the functional components of the compound. Linkers can be susceptible to or be substantially resistant to acid-induced cleavage, light-induced cleavage, peptidase-induced cleavage, esterase-induced cleavage, and / or disulfide bond cleavage at conditions under which the first functional (or other functional components) component and / or the binding protein remains active. Linkers are classified based on the presence of one or more chemical motifs such as, for example, including a disulfide group, a hydrazine group or peptide (cleavable), or a thioester group (non-cleavable). Linkers also include charged linkers, and hydrophilic forms thereof as known in the art. Suitable linkers for linking the binding protein and the first functional component of the binding compounds of the present disclosure include a natural linker, an empirical linker, or a combination of natural and / or empirical linkers. Natural linkers are derived from the amino acid linking sequence of multi-domain proteins, which are naturally present between protein domains. Properties of natural linkers such as, for example, length, hydrophobicity, amino acid residues, and / or secondary structure can be exploited to confer desirable properties to a multi-domain binding compound that includes natural linkers connecting the components of the anti-B7-H3 binding compounds of the present disclosure. The studies of linkers in natural multi-domain proteins have led to the generation of many empirical linkers with various sequences and conformations for the construction of recombinant fusion proteins. Empirical linkers are often classified as three types: flexible linkers, rigid linkers, and cleavable linkers. Flexible linkers can provide a certain degree of movement or interaction at the joined components. Flexible linkers typically include small, non-polar (e.g., Gly) or polar (e.g., Ser or Thr) amino acids, which provide flexibility, and allow for mobility of the connected components. An example of a flexible linker useful for linking the binding protein and the first functional component of the binding compounds of the present disclosure is SEQ ID NO:46. Rigid linkers can successfully keep a fixed distance between the first functional component and the binding protein of the binding compounds to maintain their independent functions, which can provide efficient separation of the first functional component and the binding protein and / or sufficiently reduce interference between the first functional component and the binding protein. Cleavable linkers can allow one to control the release of the first functional component and / or the binding protein in vivo. By taking advantage of unique in vivo processes, cleavable linkers can be cleaved under specific conditions such as the presence of reducing reagents or proteases. This type of linker can reduce steric hindrance, improve bioactivity, and / or achieve independent actions / metabolism of the first functional component and / or the binding protein after linker cleavage. Exemplary suitable linker sequences include the amino acid sequences of any one of SEQ ID NO:54 through SEQ ID NO:61. In one or more embodiments, the natural linker or empirical linker is covalently attached to the binding protein, the first functional component, or both, using bioconjugation chemistries. Bioconjugation chemistries are well known in the art and include, but are not limited to, NHS- ester ligation, isocyanate ligation, isothiocyanate ligation, benzoyl fluoride ligation, maleimide conjugation, iodoacetamide conjugation, 2-thiopyridine disulfide exchange, 3-arylpropiolonitrile conjugation, diazonium salt conjugation, 4-phenyl-3H-1,2,4-triazole-3,5 (4H)-dione conjugation, and Mannich ligation. In one or more embodiments, the natural linker or empirical linker, the first functional component, the binding protein, or combinations thereof, may include one or more unnatural amino acids that allow for bioorthogonal conjugation reactions. As used herein, “bioorthogonal conjugation” refers to a conjugation reaction that uses one or more unnatural amino acids or modified amino acids as a starting reagent. Examples of bioorthogonal conjugation reactions include, but are not limited to, Staudinger ligation, copper-catalyzed azide–alkyne cycloaddition, strain promoted [3+2] cycloadditions, tetrazine ligation, metal-catalyzed coupling reactions, or oxime-hydrazone ligations. Examples of non-natural amino acids include, but are not limited to, azidohomoalanine, 2 homopropargylglycine, 3 homoallylglycine, 4 p-acetyl-Phe, 5 p-azido-Phe, 3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid, Nɛ-(cyclooct-2-yn-1- yloxy)carbonyl)L-lysine, Nɛ-2-azideoethyloxycarbonyl-L-lysine, Nɛ-p-azidobenzyloxycarbonyl lysine, propargyl-L-lysine, or trans-cyclooct-2-ene lysine. Such amino acids may be incorporated at any location of the binding proteins of the present disclosure or at any location on any of the functional components. In one or more embodiments, the linker is derived from a small molecule, such as a polymer. Example polymer linkers include but are not limited to, poly-ethylene glycol, poly(N- isopropylacrylamide), and N,N′-dimethylacrylamide)-co-4-phenylazophenyl acrylate. The small molecule linkers generally include one or more reactive handles allowing conjugation to the binding protein, the domain, or both. In one or more embodiments, the reactive handle allows for a bioconjugation or bioorthogonal conjugation. In one or more embodiments, the reactive handle allows for any organic reaction compatible with conjugating a linker to the binding protein or the first functional component. The linker may be conjugated at any amino acid location of the binding protein. For example, the linker may be conjugated to the N-terminus, C-terminus, or any amino acid between. In embodiments where the binding compound includes more than one functional component, the additional functional components may be operably coupled to each other and / or the binding protein using one or more of the linkers disclosed herein. In one or more embodiments where the binding compound includes a binding protein and one or more functional components operably coupled by peptide linkers, the binding compound may be produced by expression in a host cell using methods known in the art. In one or more embodiments where the anti-binding compound includes a binding protein and one or more functional components operably coupled by peptide linkers, the binding compound may be produced using solid phase peptide synthesis using methods known in the art. Nucleic Acid Sequences and Host Cells In another aspect, this disclosure describes an isolated nucleic acid sequence that encodes the amino acid sequence of any embodiment of the binding compounds described herein or any component polypeptide fragment thereof. Given the amino acid sequence of any polypeptide, a person of ordinary skill in the art can determine the full scope of polynucleotides that encode that amino acid sequence using conventional, routine methods. In another aspect, this disclosure describes a host cell including any of the isolated nucleic acid sequences, binding compounds, and / or binding proteins described herein. The nucleic acid constructs of the present disclosure may be introduced into a host cell to be altered, thus allowing expression of a binding compound and / or a binding protein within the cell, thereby generating a genetically engineered cell. A variety of methods are known in the art and suitable for introduction of a nucleic acid into a cell, including viral and non-viral mediated techniques. Examples of typical non-viral mediated techniques include, but are not limited to, electroporation, calcium phosphate mediated transfer, nucleofection, sonoporation, heat shock, magnetofection, liposome mediated transfer, microinjection, microprojectile mediated transfer (e.g., nanoparticles), cationic polymer mediated transfer (e.g., DEAE-dextran, polyethylenimine, polyethylene glycol (PEG) and the like), or cell fusion. Other methods of transfection include proprietary transfection reagents such as LIPOFECTAMINE (Thermo Fisher Scientific, Inc., Waltham, MA), HILYMAX (Dojindo Molecular Technologies, Inc., Rockville, MD), FUGENE (Promega Corp., Madison, WI), JETPEI (Polyplus Transfection, Illkirch, France), EFFECTENE (Qiagen, Hilden, Germany) and DreamFect (OZ Biosciences, Inc USA, San Diego, CA). The nucleic acid constructs described herein may be introduced into a host cell to be altered, thus allowing expression within the cell of the binding compound and / or the binding protein encoded by the nucleic acid. A variety of host cells are known in the art and suitable for protein expression. Examples of typical cell used for transfection and protein expression include, but are not limited to, a bacterial cell, a eukaryotic cell, a yeast cell, an insect cell, or a plant cell such as, for example, E. coli, Bacillus, Streptomyces, Pichia pastoris, Salmonella typhimurium, Drosophila S2, Spodoptera SJ9, CHO, COS (e.g., COS-7),3T3-F442A, HeLa, HUVEC, HUAEC, NIH 3T3, Jurkat, 293, 293H, or 293F. Pharmaceutical Compositions In another aspect, this disclosure provides pharmaceutical compositions that include one or more binding compounds described herein (including binding compounds that include a binding protein and no additional functional components), formulated together with a pharmaceutically acceptable carrier. Such compositions may include one or a combination of, for example, two or more different binding compounds. As used herein, “pharmaceutically acceptable” refers to a material that is not biologically or otherwise undesirable, e.g., the material may be administered to an individual along with a binding compound without causing any undesirable biological effects or interacting in a deleterious manner with any of the other components of the pharmaceutical composition in which it is contained. A pharmaceutical composition may include one or more pharmaceutically acceptable salts. Examples of such salts include acid addition salts and base addition salts. A pharmaceutical composition also, or alternatively, may include a pharmaceutically acceptable antioxidant. Those skilled in the art are generally aware of and understand how to apply the use of pharmaceutically acceptable salts and / or pharmaceutically acceptable antioxidants. The pharmaceutical composition may be formulated with a pharmaceutically acceptable carrier. As used herein, the term “carrier” includes any solvent, dispersion medium, vehicle, coating, diluent, antibacterial, and / or antifungal agent, isotonic agent, absorption delaying agent, buffer, carrier solution, suspension, hydrogel, colloid, an accessory agent, stabilizer, protein carrier, biological carrier compound, or the like. Non-limiting examples of solvents include water, ethanol, a polyol (e.g., glycerol, propylene glycol, polyethylene glycol, and the like), a vegetable oil (e.g., olive oil), or an injectable organic ester (e.g., ethyl oleate), or combinations thereof. Non-limiting examples of a protein carrier includes keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA), ovalbumin, or the like. Non-limiting examples of a biological binding compound which may serve as a carrier include a glycosaminoglycan, a proteoglycan, or albumin. The carrier may include an organic solvent (e.g., dimethyl sulfoxide), a synthetic compound, or a synthetic polymer (e.g., a polyalkyleneglycol). Ovalbumin, human serum albumin, other proteins, polyethylene glycol, or the like may be employed as the carrier. The use of such media and / or agents for pharmaceutical active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active ingredient (i.e., the compound), its use in the therapeutic compositions is contemplated. Supplementary active ingredients also can be incorporated into the compositions. A pharmaceutical composition may also, or alternatively, may include one or more adjuvants such as, for example, a preservative, a wetting agent, an emulsifying agent, and / or a dispersing agent. In one or more embodiments, a pharmaceutical composition can include an antibacterial agent and / or an antifungal agent such as, for example, paraben, chlorobutanol, phenol sorbic acid, or the like. It may also be desirable to include isotonic agents, such as a sugar, sodium chloride, or a polyalcohol (e.g., mannitol, sorbitol, etc.) into the compositions. In addition, prolonged absorption of an injectable pharmaceutical form may be provided by including an agent that delays absorption such as, for example, aluminum monostearate or gelatin. A binding compound of the present disclosure may therefore be formulated into a pharmaceutical composition. The pharmaceutical composition may be formulated in a variety of forms adapted to a preferred route of administration. Thus, a composition can be administered via known routes including, for example, oral, parenteral (e.g., intradermal, transcutaneous, subcutaneous, intramuscular, intravenous, intraperitoneal, etc.), or topical (e.g., intranasal, intrapulmonary, intramammary, intravaginal, intrauterine, intradermal, transcutaneous, rectally, etc.). A pharmaceutical composition can be administered to a mucosal surface, such as by administration to, for example, the nasal or respiratory mucosa (e.g., by spray or aerosol). A composition also can be administered via a sustained or delayed release. A formulation may be conveniently presented in unit dosage form and may be prepared by methods well known in the art of pharmacy. Methods of preparing a composition with a pharmaceutically acceptable carrier include the step of bringing the anti-B7-H3 binding compound into association with a carrier that constitutes one or more accessory ingredients. In general, a formulation may be prepared by uniformly and / or intimately bringing the active ingredient into association with a liquid carrier, a finely divided solid carrier, or both, and then, if necessary, shaping the product into the desired formulations. To prepare pharmaceutical compositions including the anti-B7-H3 binding compounds of the present disclosure, the binding compound can be mixed with a pharmaceutically acceptable carrier or excipient. Formulations of therapeutic and diagnostic agents can be prepared by mixing with physiologically acceptable carriers, excipients, or stabilizers in the form of, e.g., lyophilized powders, slurries, aqueous solutions, lotions, or suspensions. Thus, a binding compound of the present disclosure may be provided in any suitable form including, but not limited to, a solution, a suspension, an emulsion, a spray, an aerosol, or any form of mixture. The composition may be delivered in formulation with any pharmaceutically acceptable excipient, carrier, or vehicle. Nasal spray formulations include purified aqueous solutions of the active ingredient with preservative agents and isotonic agents. Such formulations are preferably adjusted to a pH and isotonic state compatible with the nasal mucous membranes. Formulations for rectal or vaginal administration may be presented as a suppository with a suitable carrier such as cocoa butter, hydrogenated fats, or hydrogenated fatty carboxylic acids. Ophthalmic formulations are prepared by a similar method to the nasal spray, except that the pH and isotonic factors are preferably adjusted to match that of the eye. Topical formulations include the binding compound dissolved or suspended in one or more media such as mineral oil, petroleum, polyhydroxy alcohols, or other bases used for topical pharmaceutical formulations. For example, topical formulations may include a cream, an ointment, a paste, a lotion, a powder, a solid, an aerosolized foam, or a gel. Topical formulations may contain a permeation enhancer to increase the bioavailability of the active ingredient. Topical formulations may contain preservatives and / or emulsifiers. Topical formulations may be provided in the form of a transdermal patch or bandage, wherein the formulation is incorporated into a gauze or other structure and brought into contact with the skin. The formulation may further include one or more additives including such as, for example, an adjuvant, a skin penetration enhancer, a colorant, a fragrance, a flavoring, a moisturizer, a thickener, and the like. Formulations of the present disclosure suitable for oral administration may be presented as discrete units such as a tablet, a troche, a capsule, a lozenge, a wafer, or a cachet, each containing a predetermined amount of the active ingredient as a powder or granules, as liposomes, or as a solution or suspension in an aqueous liquor or non-aqueous liquid such as a syrup, an elixir, an emulsion, or a draught. The tablet, troche, pill, capsule, and the like may also contain one or more of the following: a binder such as gum tragacanth, acacia, corn starch or gelatin; an excipient such as dicalcium phosphate; a disintegrating agent such as corn starch, potato starch, alginic acid, and the like; a lubricant such as magnesium stearate; a sweetening agent such as sucrose, fructose, lactose, or aspartame; or a natural or artificial flavoring agent. When the unit dosage form is a capsule, it may further contain a liquid carrier, such as a vegetable oil or a polyethylene glycol. Various other materials may be present as coatings or to otherwise modify the physical form of the solid unit dosage form. For instance, a tablet, a pill, or a capsule may be coated with gelatin, wax, shellac, sugar, and / or the like. A syrup or elixir may contain one or more sweetening agent, preservative such as methyl- or propylparaben, an agent to retard crystallization of sugar, an agent to increase the solubility of any other ingredient (e.g., a polyhydric alcohol such as, glycerol or sorbitol), a dye, and / or flavoring agent. The material used in preparing any unit dosage form is substantially nontoxic in the amounts employed. The active ingredient may be incorporated into preparations or devices in formulations that may or may not be designed for sustained release. Formulations suitable for parenteral administration can include a sterile aqueous preparation of the active ingredient, or a dispersion of a sterile powder of the active ingredient, which are preferably isotonic with the blood of the recipient. Parenteral administration of a binding compound or pharmaceutical composition containing the same of the present disclosure (e.g., through an intravenous drip) is one form of administration. Isotonic agents that may be included in the liquid preparation include, but are not limited to, a sugar, a buffer, and / or sodium chloride. Solutions of the active ingredient may be prepared in water, optionally mixed with a nontoxic surfactant. Dispersions of the active ingredient may be prepared in, for example, water, ethanol, a polyol (such as glycerol, propylene glycol, liquid polyethylene glycols, and the like), a vegetable oil, a glycerol ester, or any mixtures thereof. Methods of Treatment In yet another aspect, this disclosure provides imaging methods and methods of treating, ameliorating, detecting, diagnosing, or monitoring a disease or a symptom or clinical sign thereof, as described herein, in a patient by administering a therapeutically effective amount of a binding compound described herein and / or a pharmaceutical composition that includes one or more anti- binding compounds described herein. As used herein, the term “treating” and variations thereof refer to reducing, limiting progression, ameliorating, or resolving, to any extent, the symptoms or clinical signs related to a condition. As used herein, “symptom” refers to any subjective evidence of disease or of a patient’s condition, whereas a “sign,” or “clinical sign” refers to an objective physical finding relating to a particular condition capable of being found by one other than the patient. A “treatment” may be therapeutic or prophylactic. “Therapeutic” and variations thereof refer to a treatment that ameliorates one or more existing symptoms or clinical signs associated with a condition. “Prophylactic” and variations thereof refer to a treatment that limits, to any extent, the development and / or appearance of a symptom or clinical sign of a condition. Generally, a “therapeutic” treatment is initiated after a condition manifests in a subject, while “prophylactic” treatment is initiated before a condition manifests in a subject. Prophylactic treatment may be administered to a subject at risk of having a condition. “At risk” refers to a subject that may or may not actually possess the described risk. In the case of a non- infectious condition, for example, a subject “at risk” for developing a specified condition is a subject that possesses one or more indicia of increased risk of having, or developing, the specified condition compared to individuals who lack the one or more indicia, regardless of the whether the subject manifests any symptom or clinical sign of having or developing the condition. The amount of the binding compound administered can vary depending on various factors including, but not limited to, the binding compound being used, the weight, physical condition, and / or age of the subject, and / or the route of administration. Thus, the absolute weight of a binding compound included in a given unit dosage form can vary widely, and depends upon factors such as the species, age, weight, and physical condition of the subject, and / or the method of administration. Accordingly, it is not practical to set forth generally the amount that constitutes an amount of binding compound effective for all possible applications. Those of ordinary skill in the art, however, can readily determine the appropriate amount with due consideration of such factors. In one or more embodiments, the method can include administering a sufficient amount of the binding compound to provide a dose of, for example, from about 100 ng / kg to about 50 mg / kg to the subject, although in one or more embodiments the methods may be performed by administering a binding compound in a dose outside this range. In some of these embodiments, the method includes administering a sufficient amount of a binding compound to provide a dose of from about 10 μg / kg to about 5 mg / kg to the subject, for example, a dose of from about 100 μg / kg to about 1 mg / kg. A single dose may be administered all at once, continuously for a prescribed period of time, or in multiple discrete administrations. When multiple administrations are used, the amount of each administration may be the same or different. For example, a dose of 1 mg per day may be administered as a single administration of 1 mg continuously over 24 hours, as two or more equal administrations (e.g., two 0.5 mg administrations), or as two or more unequal administrations (e.g., a first administration of 0.75 mg followed by a second administration of 0.25 mg). When multiple administrations are used to deliver a single dose, the interval between administrations may be the same or different. In one or more embodiments, the active ingredient may be administered, for example, from a single dose to multiple doses per week, although in one or more embodiments the method can involve a course of treatment that includes administering doses of the active ingredient at a frequency outside this range. When a course of treatment involves administering multiple doses within a certain period, the amount of each dose may be the same or different. For example, a course of treatment can include a loading dose (e.g., initial dose), followed by a maintenance dose that is lower than the loading dose. Also, when multiple doses are used within a certain period, the interval between doses may be the same or be different. In certain embodiments, a binding compound may be administered from about once per month to about five times per week. A binding compound may be administered before, during, or after the subject first exhibits a symptom or clinical sign of the condition. Treatment initiated before the subject first exhibits a symptom or clinical sign associated with the condition may result in decreasing the likelihood that the subject experiences clinical evidence of the condition compared to a subject to which the binding compound is not administered, decreasing the severity of symptoms and / or clinical signs of the condition, and / or completely resolving the condition. Treatment initiated after the subject first exhibits a symptom or clinical sign associated with the condition may result in decreasing the severity of symptoms and / or clinical signs of the condition compared to a subject to which the composition is not administered, and / or completely resolving the condition. The binding compound can be any embodiment of the binding compounds described herein having a binding protein that binds to a target. In one or more embodiments, the target is expressed on the surface of a cell. In some such cases, the target cell can include a tumor cell so that the method can involve treating cancer associated with the tumor cells. Thus, in one or more embodiments, the method can include ameliorating at least one symptom or clinical sign of the tumor or detecting the presence of a tumor. Exemplary tumors that may be treated include tumors associated with prostate cancer, lung cancer, colon cancer, rectum cancer, urinary bladder cancer, melanoma, kidney cancer, renal cancer, oral cavity cancer, pharynx cancer, pancreas cancer, uterine cancer, thyroid cancer, skin cancer, head and neck cancer, cervical cancer, ovarian cancer, and / or hematopoietic cancer. In one or more embodiments, the binding compound is administered prior to, simultaneously with, or following chemotherapy, surgical resection of a tumor, or radiation therapy. In one or more embodiments, a binding compound may be administered, for example, from a single dose to multiple doses per week, although in one or more embodiments the method can be performed by administering a binding compound at a frequency outside this range. In certain embodiments, a binding compound may be administered from about once per month to about five times per week. In one or more embodiments, the method further includes administering one or more additional therapeutic agents. The one or more additional therapeutic agents may be administered before, after, and / or coincident to the administration of a compound. As used herein, the term “co-administered” refers to two or more components of a combination administered so that the therapeutic or prophylactic effects of the combination can be greater than the therapeutic or prophylactic effects of either component administered alone. Two components may be co- administered simultaneously or sequentially. Simultaneously co-administered components may be provided in one or more pharmaceutical compositions. Sequential co-administration of two or more components includes cases in which the components are administered so that each component can be present at the treatment site at the same time. Alternatively, sequential co- administration of two components can include cases in which at least one component has been cleared from a treatment site, but at least one cellular effect of administering the component (e.g., cytokine production, activation of a certain cell population, etc.) persists at the treatment site until one or more additional components are administered to the treatment site. Thus, a co- administered combination can, in certain circumstances, include components that never exist in a chemical mixture with one another. In other embodiments, a binding compound of the present disclosure and the additional therapeutic agent may be administered as part of a mixture or cocktail. In some aspects, the administration of a binding compound may allow for the effectiveness of a lower dosage of other therapeutic modalities when compared to the administration of the other therapeutic agent or agents alone, thereby decreasing the likelihood, severity, and / or extent of the toxicity observed when a higher dose of the other therapeutic agent or agents is administered. In one or more embodiments, the method can include administering a sufficient amount of a binding compound as described herein and administering the at least one additional therapeutic agent demonstrates therapeutic synergy. In some aspects of the methods of the present disclosure, a measurement of response to treatment observed after administering both a binding compound as described herein, and the additional therapeutic agent is improved over the same measurement of response to treatment observed after administering either the binding compound or the additional therapeutic agent alone. In yet another aspect, this disclosure describes a capture assay device including any embodiment of one of the binding compounds (including a binding protein that does not include an additional functional component) described herein immobilized to a substrate. For example, a binding compound described herein can be incorporated into cell and / or ligand capture technology such as, for example, an ELISA-based assay. A substrate to immobilize the binding compound can include, for example, a cell culture plate or dish, a glass slide, or any other support than can be used to perform an assay requiring an immobilized compound. In another aspect, the present disclosure describes a method for using a binding compound described herein in molecular imaging applications including, for example, both traditional molecular imaging techniques (e.g., magnetic resonance imaging (MRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), ultrasound, photoacoustic, and fluorescence) and microscopy and / or nanoscopy imaging techniques (e.g., total internal reflection fluorescence (TIRF)-microscopy, stimulated emission depletion (STRED)-nanoscopy, or atomic force microscopy (AFM). The binding compounds described herein may have in vitro and in vivo detection, diagnostic, and / or therapeutic utilities. For example, binding compounds may be included in a detection composition for use in a detection method. The detection composition may include any carrier and / or adjuvant as described herein, or any additional carrier or adjuvant known in the art. The method generally can include allowing a binding compound that specifically binds to a target of interest with a sample that includes the target of interest, then detecting the formation of a compound:target complex. Thus, the binding compounds may be designed to include a detectable marker such as, for example, a radioactive isotope, a fluorescent marker, an enzyme, a magnetic marker, or a colorimetric marker. Select Definitions In the preceding description and following claims, the term “and / or” means one or all of the listed elements or a combination of any two or more of the listed elements; the terms “comprises,” “comprising,” and variations thereof are to be construed as open ended—i.e., additional elements or steps are optional and may or may not be present; unless otherwise specified, “a,” “an,” “the,” and “at least one” are used interchangeably and mean one or more than one; and the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). In the preceding description, particular embodiments may be described in isolation for clarity. Reference throughout this specification to “one embodiment,” “an embodiment,” “certain embodiments,” “one or more embodiments,” or “some embodiments,” etc., means that a particular feature, configuration, composition, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Thus, the appearances of such phrases in various places throughout this specification are not necessarily referring to the same embodiment of the disclosure. Furthermore, the particular features, configurations, compositions, or characteristics may be combined in any suitable manner in one or more embodiments. Thus, features described in the context of one embodiment may be combined with features described in the context of a different embodiment except where the features are necessarily mutually exclusive. For any method disclosed herein that includes discrete steps, the steps may be performed in any feasible order. And, as appropriate, any combination of two or more steps may be performed simultaneously. As used herein, the terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful and is not intended to exclude other embodiments from the scope of the invention. The term “polypeptide” refers to a sequence of amino acid residues without regard to the length of the sequence. Therefore, the term “polypeptide” refers to any amino acid sequence having at least two amino acids and includes full-length proteins, fragments thereof, and / or, as the case may be, polyproteins. The term “protein” refers to any sequence of two or more amino acid residues without regard to the length of the sequence, as well as any complex of two or more separately translated amino acid sequences. Protein also refers to amino acid sequences chemically modified to include a carbohydrate, a lipid, a nucleotide sequence, or any combination of carbohydrates, lipids, and / or nucleotide sequences. As used herein, “protein,” “peptide,” and “polypeptide” are used interchangeably. As used herein, the term “nucleic acid” or “oligonucleotide” refers to polynucleotides such as deoxyribonucleic acid (DNA) or ribonucleic acid (RNA). Nucleic acids include but are not limited to genomic DNA, cDNA, mRNA, iRNA, miRNA, tRNA, ncRNA, rRNA, and recombinantly produced and chemically synthesized molecules such as aptamers, plasmids, anti- sense DNA strands, shRNA, ribozymes, nucleic acids conjugates, and oligonucleotides. A nucleic acid may be single-stranded, double-stranded, linear, or covalently circularly closed molecule. A nucleic acid can be isolated. The term “isolated nucleic acid” means, that the nucleic acid (i) was amplified in vitro, for example via polymerase chain reaction (PCR), (ii) was produced recombinantly by cloning, (iii) was purified, for example, by cleavage and separation by gel electrophoresis, (iv) was synthesized, for example, by chemical synthesis, or (vi) extracted from a sample. A nucleic might be introduced—i.e., transfected—into cells. When RNA is used to transfect cells, the RNA may be modified by stabilizing modifications, capping, or polyadenylation. It is understood that items in a list are contemplated both as a part of the list and as separate embodiments that can exist independently of the list. EXAMPLES The present invention is illustrated by the following examples. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the invention as set forth herein. Example 1 Library construction: All 45 libraries were independently synthesized via overlap extension polymerase chain reaction (PCR) of oligonucleotides (Integrated DNA Technologies, Coralville, IA). The 129 bp product was gel extracted from a 2% agarose gel and purified via silicon spin column (Epoch Life Sciences, Missouri City, TX) per manufacturer’s instructions. The constructed libraries were amplified via PCR, concentrated via ethanol precipitation, and resuspended in 30 μL of 0.5 M sorbitol and 0.5 mM calcium chloride in dH2O. A yeast display vector pCT with a V5 epitope tag was digested with BamHI and NheI and ethanol precipitated. Library DNA that shared the same framework sequence were pooled together in equal concentrations to perform a total of ten electroporation transformations. Scaffold gene variants and linearized vector (Aga2 – HA – GS linker – library – V5) were reassembled via homologous recombination upon electroporation (Benatuil, L., Perez, J. M., Belk, J. & Hsieh, C.-M. An improved yeast transformation method for the generation of very large human antibody libraries. Protein Eng. Des. Sel. 23, 155–159 (2010); Woldring, D. R., Holec, P. V., Zhou, H. & Hackel, B. J. High-throughput ligand discovery reveals a sitewise gradient of diversity in broadly evolved hydrophilic fibronectin domains. PLoS One 10, (2015)) into S. cerevisiae yeast (EBY100; Boder, E. T. & Wittrup, K. D. Yeast Surface Display for Screening Combinatorial Polypeptide Libraries. Nat. Biotechnol. 15, 553–557 (1997)). Dilutions on an agar plate of the transformed cells were used to calculate the resulting library diversities. Yeast were propagated in SD-CAA medium (16.8 g sodium citrate dihydrate, 3.9 g citric acid, 20.0 g dextrose, 6.7 g yeast nitrogen base, 5.0 g casamino acids, filled to 1 L dH2O) at 30 ºC with agitation at 250 rpm. Proteins were displayed on the yeast surface by switching to galactose-containing SG-CAA medium (10.2 g sodium phosphate monobasic monohydrate crystal (Na2HPO47∙H2O), 8.6 g sodium phosphate dibasic heptahydrate (NaH2PO4∙H2O), 19.0 g galactose, 1.0 g dextrose, 6.7 g yeast nitrogen base, 5.0 g casamino acids, filled to 1 L dH2O) and left to grow overnight at 30 ºC, 250 rpm. On-yeast protease assay: Proteinase K (New England Biolabs, Ipswich, MA) was diluted in phosphate-buffered saline with 0.1% albumin (PBSA). Thermolysin (Promega, Madison, WI) was reconstituted to 1 mg / mL in 50 mM Tris at pH 8 with 0.5 mM calcium chloride and diluted with PBSA. Dilutions for both proteases, 1:16000 and 1:200 for proteinase K and thermolysin, respectively, were prepared on ice the day of the experiment. Dilutions were determined by preliminary titrations to obtain a broad distribution of cells across all FACS gates. A total of 10 million yeast expressing a collection of all libraries were centrifuged at 12,000 × g for 1 minute, aspirated, resuspended in 1 mL cold PBSA, centrifuged, resuspended in 50 μL in PBSA, and placed on ice. A total of 50 μL diluted enzyme was added to the cells and mixed via pipetting. The 100 μL of cell / enzyme solution was placed in a 4 °C pre-chilled PCR block where a preset program heated the mixture to 37 ºC or 55 ºC (proteinase K) or 55 ºC or 75 ºC (thermolysin) for 10 minutes and returned to 4 °C. The cell / enzyme mixture was diluted with 1 mL of PBSA, centrifuged at 12,000 g for 1 minute, and aspirated. The cells were resuspended in PBSA containing chicken–anti–HA antibody (Abcam, Waltham, MA) and mouse–anti–V5 (Bio-Rad, Hercules, CA), and rotated for 30 min at room temperature. Cells were pelleted, washed, and resuspended in PBSA containing goat–anti–chicken AlexaFluor488 antibody (Invitrogen, Carlsbad, CA) and goat–anti–mouse AlexaFluor647 antibody (Invitrogen, Carlsbad, CA) and incubated at 4 ºC for 20 min without exposure to light. Finally, cells were pelleted, washed, and stored until sorting. Cells were separated via FACS into eight populations based on the V5 to HA ratio. Gate boundaries drawn were determined by the location of the libraries in a no enzyme control. The boundary for the least protease resistant gate (lowest V5:HA ratio) was drawn to include only 1% of the control population where the primary anti-V5 labeling antibody was omitted. All eight gates were drawn to contain equal percentages of cells collected. Collected cells were centrifuged and immediately prepared for Illumina sequencing. Split GFP assay: Scaffold variant gene libraries were extracted with NheI-HF and BamHI-HF, ligated into pET-gfp11 plasmid (Golinski, A. W. et al. High-throughput developability assays enable library- scale identification of producible protein scaffold variants. Proc. Natl. Acad. Sci. U. S. A. 118, 1– 11 (2021)), electroporated into NEB 10-beta electro-competent E. coli, and extracted via miniprep. E. coli cells that were pre-transformed with pBAD-gfp1-10 (Golinski, A. W. et al. High-throughput developability assays enable library-scale identification of producible protein scaffold variants. Proc. Natl. Acad. Sci. U. S. A.118, 1–11 (2021)) were transformed, via electroporation, with scaffold-GFP11plasmids, aliquoted, and stored at -80 °C to be used on the day of the experiment. Frozen aliquots of cells were thawed, grown in 5 mL LB + ampicillin + kanamycin overnight, diluted to an optical density at 600 nm (OD600) of 0.1 and grown for 90 minutes. Scaffold-GFP11production was induced by adding 5 μL 0.5 mM isopropylthio-β- galactoside (IPTG) for two hours at 37 °C. GFP1-10production was induced by adding 500 μL 2 mg / mL arabinose and continued to grow for two hours at 37 °C. Afterwards, cells were centrifuged at 3200 g for 3 minutes at 4 °C and resuspended in 1 mL of PBSA and stored on wet ice. FACS was used to separate cells based upon the GFP signal into six equally spaced (log scale) gates. An average of 2.4 million cells were collected, centrifuged at 3200 g for 10 minutes, and prepared for Illumina deep sequencing without further growth. Magnetic-activated cell sorting: Yeast were grown at 30 °C and induced to display proteins on the cell surface following the yeast surface display protocol. For each campaign, 33 pmoles of biotinylated target protein was added to 100 μL of PBSA + 10 μL of Biotin Binder DYNABEADS (Invitrogen, Carlsbad, CA) and incubated at 4 °C for 2 hours. Beads were washed with 1 mL PBSA via magnetic capture. Yeast equivalent to 15-fold of the library diversity were centrifuged, washed with PBSA, combined with 10 μL of unconjugated DYNABEADS, and incubated at 4 °C on a rotator for 2 hours. Cell / bead mixture was placed on a magnet for 5 minutes before collecting unbound cells. Unbound cells were placed in a new 2 mL tube along with 10 μL of IgG-conjugated beads (as a negative control) and incubated at 4 °C on a rotator for 2 hours. The cell / bead mixture was placed on the magnet; unbound cells were collected and mixed with 10 μL of target-conjugated beads for another 2 hours. Cell / bead mixture was placed on a magnet for 5 minutes before collecting bound cells and discarding unbound cells. Beads from all steps were subsequently washed twice using cold PBSA and placed in 100 mL SD-CAA to grow overnight. Cells bound to bare beads and IgG negative control were also grown to determine population enrichment of binders.100x and 2,000x dilutions were added to YPD plates for diversity calculations. Collected target-bound yeast were grown and induced for additional sorting. Three sorts were performed before cells were prepared for Illumina deep sequencing. Library preparation for Illumina deep sequencing: Cells were centrifuged at 3220 g for 3 minutes and resuspended in 200 μL Zymo solution 1 + 2 μL β-mercaptoethanol + 10 μL ZYMOLASE (5 U / μL; Zymo Research, Irvine, CA). Solution was incubated at 37 °C for 1 hour. Afterwards, 200 μL of MX2 and 300 μL of MX3 (Epoch Life Sciences, Missouri City, TX) was added and mixed with the solution and centrifuged at 12,000 g for 8 minutes. Supernatant was transferred to Epoch DNA column and centrifuged at 8000 g for 1 minute, followed by two washes with WS, and eluted. 15 μL of eluted DNA + 2 μL ExoI + 1 μL Lambda Exo + 2 μL Lambda Buffer was mixed and incubated on a PCR block at 30 °C for 90 minutes followed by 80 °C for 20 minutes to inactivate enzymes. Standard PCR protocol was followed using Q5 High-fidelity polymerase (New England Biolabs, Ipswich, MA), followed by a ExoI cleanup.2 μL 1:10 dilution of ExoI was directly added to PCR tubes and incubated at 37 °C for 30 minutes followed by 80 °C for 20 minutes to inactivate the enzymes. 1 μL from the PCR tube was taken and used for a subsequent PCR using the Illumina specific forward primer and reverse index primers. Resulting PCR products were purified by gel electrophoresis. Illumina ISEQ sequencing was performed. Protein sequence and library developability score calculation: The Usearch (Edgar, R. C. Search and clustering orders of magnitude faster than BLAST. Bioinformatics 26, 2460–2461 (2010)) algorithms was used to merge, align, filter, and identify unique sequences from raw fasta files. Afterwards, homemade python scripts were developed for data preprocessing: remove sequences with stop codons, assign each sequence to its respective library, and calculate library scores. Library scores were calculated by taking a gate-weighted dot product between the number of reads found in each gate with a respective gate weight (from top gate 8 to bottom gate 1). Each library score was normalized by subtracting the overall library mean and dividing by the standard deviation (i.e. computing the z-score). Independent t-tests were used to determine statistical significances between library scores using the open source SciPy package. Protein sequence and library evolvability score calculation: Evolvability is assessed via two components: diversity (number of unique binders) and binding strength (relative abundance of each clone). The evolvability score of each variant is the quartic root of the number of sequencing reads to dampen dominant clones. Library evolvability scores are computed by taking the log2of the ratio between the sum of variant scores from that library and the sum of all variant scores subtracted by the log2of the ratio between the sum of variant scores from that library and the sum of all variants scores in the initial unsorted population. Calculation of residue enrichment scores: To investigate the effect of any residue’s presence within the paratope on overall library developability, the frequency of every residue within the given paratope for every sequence in the library was calculated. A line of best fit was calculated based on the stability as a function of frequency across all residues. The slope of the linear regression was used as a proxy for determining the relationship between a residue’s frequency and the resulting library’s stability. Sitewise residue enrichment scores were calculated by finding the log2of the frequency a residue was seen in the top gate normalized to the sitewise frequency of all residues from an unsorted population. Affinity maturation: DNA from the naïve VEGF-binding population was extracted via ZYMOPREP, as detailed herein. Genes were amplified using error-prone PCR in 50 μL reactions (5 μL NEB ThermoPol reaction buffer, 2.5 μL 10 μM forward primer, 2.5 μL 10 μM reverse primer, 1 μL 10 mM dNTPs, 10 μL 8-oxo-dGTP + dPTP 10 μM each, 0.25 μL Taq polymerase, fill to 50 μL ddH2O), concentrated via ethanol precipitation, and resuspended in 30 μL of 0.5 M sorbitol and 0.5 mM calcium chloride in dH2O. Diversified genes were shuttled into the yeast display system as detailed herein for original library creation. Variants were iteratively sorted thrice via MACS against biotinylated human VEGF121 protein (Acro biosystems, Newark, DE). A more stringent sort was conducted via a monovalent MACS sort at 100 nM VEGF, followed by selection of the top 1% of strongest binders via FACS at 10 nM VEGF. The resulting binding population was subjected to proteinase K at 55 ºC, and the top 5% of stable binders were sorted via FACS. The final binding population was then deep sequenced. Protein production and purification protocol: The genes for 24 clones affinity matured for binding to VEGF were synthesized by Integrated DNA Technologies (Coralville, IA) ligated into a pET vector with a C-terminal His6tag, and transformed into NEB T7 express (New England Biolabs, Ipswich, MA) competent E. coli. Single colonies were grown in 5mL of LB + kanamycin at 37 ˚C, 250 rpm overnight, diluted in 100 mL of LB + kanamycin to yield an OD600of 0.1, and incubated at 37 ˚C, 250 rpm until OD600~ 1.0. Protein production was induced by adding 0.5 mM IPTG and incubated for 2 hours at 37 ˚C, 250 rpm. Cells were then pelleted at 3200g for 15 minutes and aspirated, resuspended in 1 mL of lysis buffer (2.07 g sodium phosphate monobasic monohydrate crystal (NaH2PO4∙H2O), 9.38 g sodium phosphate dibasic heptahydrate (Na2HPO4∙7H2O), 29.2 g sodium chloride, 50 mL glycerol, 3.1g CHAPS, 1.7 g imidazole, filled to 1 L of filtered ddH2O) with protease inhibitors (1 tablet per 10 mL lysis buffer), and freeze-thaw thrice at -80 ºC for mechanical disruption. Lysate was centrifuged at 12,000g for 10 minutes at 4 ºC, filtered with a 0.22 μm filter and rotated with 100 μL of Cobalt HisPur resin at 4 ºC for 5 minutes. Lysate + cobalt resin was washed column with 1 mL of wash buffer (PBS, 30 mM imidazole). Ligand was eluted with 100 μL of elution buffer (PBS with 300 mM imidazole) via centrifugation at 700 g for 1 minute and flash frozen for long term storage. Quantifying protein recombinant yield via SDS-PAGE: 12 μL of the protein sample (or lysozyme calibrant) along with 4 μL of NuPAGE LDS buffer (4x) and 1 μL of β-mercaptoethanol were combined and heated at 99 ºC for 10 minutes, and loaded into a 1.5mm NuPAGE 4-12% Bis-Tris (Invitrogen, Ipswich) gel and ran at 180 V for 30 minutes. The gel was stained with SIMPLYBLUE SAFESTAIN, imaged, and analyzed using the ImageJ software to quantify the protein concentration relative to the lysozyme concentration controls. Measuring secondary structure and melting temperature using circular dichroism: Protein samples were dialyzed in SLIDE-A-LYZER MINI Dialysis (10K molecular weight cutoff) cup in 10 mM sodium phosphate buffer (1.01g sodium phosphate dibasic heptahydrate (Na2HPO4∙7H2O), 169.7 mg sodium phosphate monobasic monohydrate (NaH2PO4∙H2O), up to 500 mL ddH2O, pH 7.4). A minimum of four buffer exchanges were performed to ensure maximum removal of imidazole. Protein samples were diluted between 0.1 – 0.2 mg / mL in 200 μL of 10 mM sodium phosphate buffer and loaded into the Picoland Jasco J815 Circular Dichroism spectropolarimeter. Default system parameters were used. Settings for the temperature sweep included sampling every 1 ºC between 15 °C – 95 ºC at a ramp rate of 3 ºC / min and a wait time of 6 seconds monitoring at the 218 nm wavelength. Affinity titration experiments via yeast surface display: Genes were shuttled to the yeast plasmid display vector pCT via digestion / ligation with NheI and BamHI, and transformed into EBY100 yeast using the Frozen-EZ yeast transformation kit (Zymo Research) following manufacturer’s protocols. Yeast were propagated in SD-CAA medium at 30 ºC, 250 rpm, and induced to display protein by switching to galactose-containing SG-CAA medium and left to grow overnight at 30 ºC, 250 rpm. For each affinity titration sample, 1-2 million cells were washed with PBSA and incubated with biotinylated human VEGF121 (0.1 – 250 nM; Acro Biosystems, Newark, DE) until equilibrium was approached. Cells were washed with PBSA, resuspended in PBSA containing mouse–anti–V5 (Bio-Rad, Hercules, CA), and rotated for 30 min at room temperature. Cells were pelleted, washed, and resuspended in PBSA containing AlexaFluor488 streptavidin conjugate (Invitrogen, Carlsbad, CA) and goat–anti–mouse AlexaFluor647 antibody (Invitrogen, Carlsbad, CA) and incubated at 4 ºC for 20 min shielded from light. Cells were pelleted, washed, and analyzed on a BD Accuri C6 Plus flow cytometer. The median AlexaFluor 488 fluorescence of the cells displaying AlexaFluor 647 signal was recorded, corrected against a no-target control, normalized relative to the maximum within the replicate. Affinity was computed via a global fit of a 1:1 binding model using Excel’s GRG nonlinear optimization solver. Example 2 Library design and construction: Genetic libraries were constructed based upon four synthetic βαββ proteins (Rocklin, G. J., Chidyausiku, T. M., Goreshnik, I., Ford, A., Houliston, S., Lemak, A., Carter, L., Ravichandran, R., Mulligan, V. K., Chevalier, A., Arrowsmith, C. H. & Baker, D. Global analysis of protein folding using massively parallel design, synthesis, and testing. Science (80-. ). 357, 168–175 (2017)). The four most stable proteins were chosen: EHEE_rd2_0005, EHEE_rd2_0008, EHEE_rd2_0875, and EHEE_rd3_0124, herein named framework (FW) 1, 2, 3, and 4. Genetic libraries were constructed for each framework, with potential paratopes created by diversifying the sequence encoding for the surfaces of either the D-helix, the loops connecting the E-sheets and D-helix, or the E-sheets. In general, sites were diversified using NNK degenerate codons, which can encode all 20 amino acids, but reduces the probability of stop codons (relative to NNN). At several sites, mutation stability data from 1 indicates that P is very destabilizing. At any site where the consensus stability score measured for proline was more than 17% below the wild-type, P was excluded from the diversity (FIG.23 clarifies design). Parallel libraries were also made with full NNK diversity for comparison. The eight sites encoding for the loops connecting the first β-strand to the α-helix, and second β-strand to the third β-strand were diversified. Site 10 (the ninth diversified site) on the β- strand directly adjacent to the loop was also diversified in proteins FW1 and FW2 to allow for wild-type E or the neutral mutant Q in case charge repulsion interfered with target binding. In FW3, this site was diversified to allow for wild-type R and Q. In the second library, nine sites on the solvent-exposed surface of the a-helix were diversified. Stability data showed that many amino acids at site 21 result in large decreases in stability compared to WT, so an HDB codon was used, which excluded P, A, T, V, D, E, and G. For the β-sheet libraries, seven to eleven sites on the solvent-exposed face of the β-sheet were diversified. To assess the effect of paratope size and location, eight, nine, or eleven sites were diversified across all three β-strands. To assess the effect of the number of diversified strands, libraries were also made with seven or eight sites diversified on pairs of β-strands. Libraries are summarized in FIG.1, FIG.2, and FIG.23. Gene and pCT80 vector Preparation: The 43 genetic libraries were created via polymerase chain reaction (PCR) using oligonucleotides encoding for the library purchased from Integrated DNA Technologies (Coralville, IA). The 44thlibrary, FW3 β AB7, was designed incorrectly, and was caught late in the study, so it is not included in the analysis. An initial polymerase chain reaction (PCR) was run to combine the oligos using the following PCR conditions: 1X Q5 reaction buffer, 200 μM dNTPs, 0.5 μM primers, 0.005 μM of each oligonucleotide, and 0.02 U / μL Q5 Hot Start High- Fidelity DNA Polymerase (New England Biolabs, Ipswich, MA) in 50 μL of deionized water (dH2O) and was run at 98 °C for 30 seconds (s), (98 °C for 10 s, 60 °C for 20 s, 72 °C for 20 s) for 40 cycles, and 72 °C for 120 s. Full length gene sequences were isolated using agarose gel electrophoresis and purified via gel extraction. Amplification of genes was performed with PHUSION polymerase under the following conditions: 10 ng of total DNA template, 0.02 U / μL PHUSION polymerase, 1x PHUSION buffer, 0.5 μM primers, 200 μM dNTPs in 400 μL of dH2O, split into 8 separate reactions and was run at 98 °C for 30 s, (98 °C for 10 s, 64 °C for 20 s, 72 °C for 20 s) for 30 cycles, and 72 °C for 120 s. DNA was purified via ethanol precipitation prior to electroporation. The 40 amino acid proline / alanine / serine linker (Stern, L. A., Schrack, I. A., Johnson, S. M., Deshpande, A., Bennett, N. R., Harasymiw, L. A., Gardner, M. K. & Hackel, B. J. Geometry and expression enhance enrichment of functional yeast-displayed ligands via cell panning. Biotechnol. Bioeng.113, 2328–2341 (2016)) was appended to the native linker in the yeast plasmid display vector pCT (Boder, E. T. & Wittrup, K. D. Yeast surface display for screening combinatorial polypeptide libraries. Nat. Biotechnol.15, 553–557 (1997)) with the MYC epitope peptide tag replaced with a V5 tag, and the sequence was confirmed via Sanger sequencing. The plasmid was miniprepped, digested with NheI-HF restriction enzyme (New England Biolabs, Ipswich, MA) and BamHI-HF (New England Biolabs, Ipswich, MA) restriction enzyme at 37 °C for four hours, and purified via ethanol precipitation. Yeast Transformation: Competent EBY100 cells were prepared prior to electroporation as described (Woldring, D. R., Holec, P. V., Zhou, H. & Hackel, B. J. High-throughput ligand discovery reveals a sitewise gradient of diversity in broadly evolved hydrophilic fibronectin domains. PLoS One 10, e0138956 (2015)). Cells were grown overnight to an optical density at 600 nm of 1.4 and washed with cold dH2O and buffer E (1.0 M sorbitol, 1 mM CaCl2). Cells were incubated at 30 °C for 30 minutes with a lithium acetate solution (0.1 M lithium acetate, 10 mM Tris, 1mM ethylenediaminetetraacetic acid, pH 7.5 and 10 mM dithiothreitol). Cells were subsequently washed with cold buffer E and resuspended in buffer E alongside gene libraries (200 pmol of insert) and vector (6 ug of digested vector). Gene libraries were combined into four groups based on their parental framework before electroporation. Cells were electroporated at 1.2 kV and 25 μF and grown in YPD medium (10 g / L yeast extract, 10 g / L peptone, 20 g / L dextrose) for 1 hour at 30 °C before being switched to SD media (16.8 g / L sodium citrate dihydrate, 3.9 g / L citric acid, 20 g / L dextrose, 6.7 g / L yeast nitrogen base, and 5 g / L casamino acids) for overnight growth and induction at 30 °C. Protein surface expression was induced by switching media from SD + chloramphenicol to SG + chloramphenicol (10.2 g / L sodium phosphate dibasic heptahydrate, 8.6 g / L sodium phosphate monobasic monohydrate, 19 g / L galactose, 1 g / L dextrose, 6.7 g / L yeast nitrogen base, 5 g / L casamino acids) at 20 °C. Epitope Labeling: Cells were labeled for flow cytometry analysis by labeling the HA and V5 tags. One million yeast cells were stained at 50 ng chicken anti-HA antibody (Abcam, Waltham, MA), 50 ng mouse anti-V5 antibody (Bio-Rad, Hercules, CA) in 50 μL PBSA and 50 ng Goat anti chicken Alexa488 (Invitrogen, Carlsbad, CA) and 50 ng Goat anti mouse Alexa647(Invitrogen, Carlsbad, CA) for 20 minutes at 4oC and washed with PBSA. Protease Assays: Five million yeast cells per 100 μL PBSA were treated with a protease (thermolysin or proteinase K) for ten minutes at 37 °C, 55 °C, or 75 °C and washed with cold PBSA before epitope labeling (HA and V5 antibodies). Cells were treated at 10-5U / μL proteinase K at 37oC and 55oC and at 2 μg / mL thermolysin at 55oC and at 10 μg / mL thermolysin at 75oC. Cells were labeled with epitope tags as previously described. Cells were gated during FACS by drawing a gate around the HA+, V5+ population, and within that population drawing diagonal gates (V5:HA ratio) consisting of the top 5%, next 10%, next 15%, and bottom 70% of cells. Previous experiments were gated by sorting a population of cells that was not treated with protease and drawing a gate around cells that did not lose their pretreatment expression, a gate around HA+, V5- cells, and two approximately equal cell gates in between. To combine these, earlier trials with percentages in the top gate close to one of the later cutoffs were used. Cells were collected using FACS. Split GFP Preparation: Constructed oligo DNA from the yeast library pre-electroporation was amplified and digested using NheI and BamHI. The same amplification protocol from above was used, and DNA was restriction enzyme digested using 1 ug DNA, 1X CutSmart Buffer, 1 μL NheI-HF and 1 μL BamHI-HF in 50 μL at 37oC for 2 hours. DNA was run on a 2% agarose gel, and gel extracted using a ZYMOCLEAN gel DNA recover kit into 10 μL elution buffer using manufacturer’s protocol (Zymo Research Company, Irvine, CA). pET-GFP11 vector (Golinski, A. W., Mischler, K. M., Laxminarayan, S., Neurock, N. L., Fossing, M., Pichman, H., Martiniani, S. & Hackel, B. J. High-throughput developability assays enable library-scale identification of producible protein scaffold variants. Proc. Natl. Acad. Sci. U. S. A.118, e2026658118 (2021)) was digested with NheI and BamHI (2 ug DNA, 5 μL cutsmart, 1 μL NheI, 1 μl BamHI, 1 μL CIP in 50 μL at 37oC for 2 hours). Digested vector was run on a 0.75% agarose gel, and gel extracted into 10 μL dH2O using a ZYMOCLEAN gel DNA recovery kit using manufacturer’s protocol. All ligations were prepared on ice.0.1 pmol digested vector, 0.5 pmol digested insert, 10 μL ligase buffer, 10 μL ATP, and 5 μL of 2,000,000 U / mL T4 ligase were combined in 100 μL following manufacturer protocol and run at 22oC for 15 min and 60oC for 10 min (New England Biolabs, Ipswich, MA). DNA was cleaned using a Qiagen minelute kit and were eluted into 10 μL elution buffer following manufacturer’s protocol (Qiagen, Germantown, MD). Six ligations were performed. Four included a DNA library derived from one of the four selected βαββ parent frameworks, one included DNA from all four parents added in at equal amounts, and one included DNA from all four parents added at equal amounts and four percent from the high and low stability controls. βαββ ligations were electroporated into electrocompetent NEB5ჴ cells using manufacturer’s protocols (New England Biolabs, Ipswich, MA). Cells were outgrown at 37oC for one hour and grown in LB + kanamycin overnight. Plate dilutions were made to calculate diversities. βαββ-GFP11 plasmids (with kanamycin resistance) were produced in these bacteria cells and extracted via miniprep. SHUFFLE cells containing pBAD GFP1-10 (Golinski, A. W., Mischler, K. M., Laxminarayan, S., Neurock, N. L., Fossing, M., Pichman, H., Martiniani, S. & Hackel, B. J. High-throughput developability assays enable library-scale identification of producible protein scaffold variants. Proc. Natl. Acad. Sci. U. S. A.118, e2026658118 (2021)) were made electrocompetent by adding 100 μL of an overnight starter culture into 100 mL of SOB (20 g / L tryptone, 5 g / L yeast extract, 0.584g / L NaCl, 0.186 g / L KCl, 1.204 g / L MgSO4, pH 7.5) + ampicillin and grown at 30oC until the OD at 600 nm reached 0.5. The culture was then incubated on ice for 15 minutes, centrifuged down, then washed twice with 10% glycerol in water. Cells were spun down, supernatant was poured off, and cells were resuspended in the residual glycerol. Competent cells were flash frozen with liquid nitrogen and stored at -80oC until needed. βαββ ligations were electroporated into electrocompetent SHUFFLE cells using the previously extracted βαββ-GFP11 plasmid.25 μL of thawed electrocompetent SHUFFLE cells were mixed with 20 ng of plasmid and shocked at 2 kV, 200 Ω, and 25 μF in a cold 1 mm electroporation cuvette. Cells were resuspended in SOB and outgrown at 30oC for one hour and grown in LB + ampicillin + kanamycin (LAK) overnight. An average of 4.9×104transformants (range: 5.1×102– 2.2×105) per sublibrary for a total of 2.1×106variants was achieved. Cells were thawed and grown up overnight in LAK. Cells were reset to OD at 600 nm of 0.1 and grown at 30 °C for 1.5 hours at 30oC. Protein production of target protein was induced by 0.5 mM IPTG for 2 hours at 37oC, resuspended in fresh LAK and grown for an hour at 37 °C, and then protein production of GFP 1-10 was induced via arabinose for 2 hours at 37 °C. Cells were washed with PBSA, and samples were analyzed via flow cytometry. A gate was drawn over GFP+ cells, and of that population, gates around the top 10%, next 15%, next 25%, and bottom 50% of cells were collected. Magnetic Activated Cell Sorting (MACS): For all targets besides IRA, streptavidin beads were labeled with biotinylated IgG (Rockland Immunochemicals, Pottstown, PA) (33 pmol which yields 5 million IgG per bead) or biotinylated target (6.7 pmol which yields 1 million target protein per bead). The targets were CD22 (R&D Systems, Minneapolis, MN), PSMA (Sino Biological, Wayne, PA), Tem8 (R&D Systems), B7-H3 (Sino Biological), or NKp46 (Acro Biosystems, Newark, DE). For IRA, anti- mCherry beads (ChromoTek, Hauppauge, NY) were used and were labeled with mCherry as the negative control, or lysate from IRA-mCherry producing HEK cells. Magnetic-activated cell sorting (MACS) was performed on samples with an initial depletion against bare streptavidin beads, a depletion against IgG, and an enrichment sort against the target protein. Yeast displaying ligands were incubated against each for 2 hours at 4 °C with constant rotation. In depletion steps, unbound cells were passed on to the next bead population and bound cell:bead conjugates were washed for comparison with the enrichment sort; in the enrichment step, beads were washed with PBSA and retained yeast were grown in SD media. First sorts involved one PBSA wash, second sorts involved 2 washes, and third / fourth sorts involved 3 washes. Cycles of growth, induction, and sorting were repeated until enrichment of specific target binders was observed. Diversities were obtained by dilution and colony development on YPD plates. Binding Checking: Binding of enriched target binders was evaluated via flow cytometry by incubating with target (or IgG negative control) at 100 nM and 0 nM.1 million yeast cells were incubated with biotinylated target at 100 nM, and washed with PBSA. Cells were then incubated with 50 ng mouse anti-V5 antibody (Bio-Rad, Hercules, CA) in 50 μL PBSA for 10 minutes and 50 ng streptavidin-Alexa488 (Invitrogen, Ipswich, MA) and 50 ng goat anti-mouse Alexa647(Invitrogen, Ipswich, MA) for 15 minutes at 4 °C and washed with PBSA. Binding was assessed by comparing Alexa488 signal between the 0 nM and 100 nM populations. Fluorescence activated cell sorting (FACS): Yeast expressing binding proteins were sorted via fluorescence-activated cell sorting (FACS). Sorts were performed at varying concentrations and were labeled via the same method for binding checking. For 100 nM sorts, all cells that had signal above background were collected, while for more stringent sorts (such as 10 nM), a subset of the highest affinity clones were grabbed. Deep sequencing of the binding populations was performed via ISEQ. Mammalian Cell Culture: HEK293T cells expressing IRA-mCherry were grown at 37 °C in Dulbecco’s Modified Eagle Medium (DMEM) with 10% fetal bovine serum and 1% penicillin-streptomycin. Cells were washed with PBS and detached with 2 mL of 0.05% trypsin / ^ethylenediaminetetraacetic acid (EDTA).5 mL of DMEM media prewarmed to 37oC was added to inactivate the trypsin, cells were spun down at 500 g for 3 minutes and either diluted for further growth or lysed, essentially as described (Tillotson, B. J., Cho, Y. K. & Shusta, E. V. Cells and cell lysates: A direct approach for engineering antibodies against membrane proteins using yeast surface display. Methods 60, 27–37 (2013)). When lysed, cells were washed three times with 5 mL of ice-cold PBS.200 μL of cell lysis buffer (Abcam, Cambridge, MA) + protease inhibitor cocktail was added, and cells were incubated for 20 minutes at 4oC under rotation. Cell debris was removed via centrifugation at 15,000 g for 20 minutes. Deep Sequencing DNA Extraction: DNA from sorted yeast populations (for protease stability assays and binding assays) was extracted using ZYMOLASE (Zymo Research Company, Irvine, CA). All collected cells from yeast protease assays or 4×107yeast from binding populations were suspended in 200 μL ZYMOLASE solution 1 (50 mM Phosphate Buffer, PH 7.5, 1M Sorbitol), with 10 mM beta- mercaptoethanol and 0.24 U / μL ZYMOLASE at 37 °C for 4 hours. One freeze thaw cycle was performed, and 200 μL MX2 and 400 μL MX3 were added, and centrifuged. The supernatant was cleaned using silica column purification and eluted into 32 μL elution buffer or dH2O.15 μL of the resulting DNA was mixed with 2 μL Exo I exonuclease, 1 μL lambda exonuclease, and 2 μL lambda exonuclease buffer and incubated at 30 °C for 90 minutes to degrade interfering genomic DNA and inactivated at 80 °C for 20 minutes. Post exonuclease treatment, DNA was cleaned using silica column purification, and eluted again into 32 μL elution buffer or dH2O. DNA from split-GFP populations was extracted via miniprep.15×107cells were used, and DNA was eluted into 32 μL dH2O or elution buffer. Illumina Sequencing Prep: Two rounds of PCR reactions were performed to amplify template and to add genetic barcodes and Illumina adaptors. The first PCR was composed of 1X Q5 buffer, 200 μM dNTPs, 0.5 μM forward and reverse primers, 15 μL of the DNA for yeast DNA or 5 μL of the DNA for bacterial DNA, 0.02 U / μL Q5 High-Fidelity DNA Polymerase in 50 μL, and was run at 98oC for 30 s, (98oC for 10 s, 62oC for 20 s, 72oC for 20 s) for 16 cycles, and 72oC for 120 s. Primers were removed by addition of 4 U of Exonuclease I (final concentration 0.077 U / μL) for 30 minutes at 37oC, and 20 minutes at 80oC for enzyme inactivation. The second PCR added barcodes unique to each gate, protease treatment, and trial. The second PCR was composed of 1x Q5 buffer, 200 μM dNTPs, 0.5 μM forward and reverse primers, 1.5 μL of the first PCR product, and 0.02 U / μL Q5 High-Fidelity DNA Polymerase in 50 μL, and was run at 98oC for 30 s, (98oC for 10 s, 67oC for 20 s, 72oC for 20 s) for 16 cycles, and 72oC for 120 s. DNA was purified by gel extraction, and concentration was measured. DNA from multiple PCRs was combined for Illumina sequencing. Illumina Sequencing / Analysis: DNA was sequenced via ISEQ and MISEQ runs by the University of Minnesota Genomics Center. Sequence analysis was performed with a combination of in-house and community code including USearch (Edgar, R. C. Search and clustering orders of magnitude faster than BLAST. Bioinformatics 26, 2460–2461 (2010)) to merge, align, and filter the sequences. Testing Individual Protein Variants Plasmid Digestion and Ligation: pET production vector with a C-terminal His6tag was digested with NheI and BamHI as previously described. Scaffold DNA was extracted from yeast, purified with exonucleases, amplified via PCR, digested with NheI and BamHI, and ligated to vector as previously described. Transformation : NEB T7 Express competent E. coli or NEB SHUFFLE T7 Express Competent E. coli were transformed essentially via manufacturer’s protocol (New England Biolabs, Ipswich, MA). A tube of cells was thawed on ice and split into three tubes. Each third was mixed with 2-5 μL of purified ligation reaction mixture and mixed via flicking. The mixture was placed on ice for 30 minutes, heat shocked at 42oC for 10 seconds (T7) or 30 seconds (SHUFFLE) and returned to ice for 5 more minutes.950 μL of room temperature SOC was added, and cells were outgrown at 37oC for 60 minutes at 250 rpm.50 μL of cell mixture was added to a LB (10 g / L tryptone, 5 g / L yeast extract, 10 g / L NaCl, and 16 g / L agar) + kanamycin plate for overnight growth. Colonies extracted from the plate were grown overnight in 5 mL of LB (10 g / L tryptone, 5 g / L yeast extract, 10 g / L NaCl) + kanamycin and sequenced via sanger sequencing. Protein Production and Purification: A starter culture was used to seed a 100 mL culture of LB + kanamycin at an OD at 600 nm of 0.1 which was grown to OD at 600 nm of 0.5 - 1. Isopropylthio-β-galactoside (IPTG) was added to yield 0.5 mM IPTG, and cells were grown for 2 hours at 37 °C (T7) or 4 hours at 30 °C (SHUFFLE). Cells were pelleted and resuspended in 1 mL of lysis buffer with protease inhibitor (9.38 g / L sodium phosphate dibasic heptahydrate, 2.07 g / L sodium phosphate monobasic monohydrate, 29.2 g / L NaCl, 5% glycerol, 3.1 g / L CHAPS, and 1.7 g / L imidazole). Cells were frozen / thawed four times and centrifuged at 12,000 × g for 10 minutes at 4oC. The supernatant was filtered with a 0.22 μm filter. 100 to 150 HisPur μL of cobalt resin was mixed with cell lysate and placed in a fritted column on a vacuum manifold. Protein / resin was washed five times with 30 mM imidazole in 1x PBS, and once with 50 mM imidazole in PBS. Protein was eluted with 100-350 μL of 300 mM imidazole in PBS, flash frozen with liquid nitrogen, and stored at -80 °C until use. Expression Measurement: Protein was run on an SDS-PAGE gel to compare concentration. Gels were loaded with a mixture of 12 μL protein sample, 4 μL LDS Buffer (4x), and 0.5 μL β-mercaptoethanol that had been preboiled at 99oC for 5 minutes. Samples were run at 185 V for 25 minutes. Lysozyme controls at 0.5 mg / mL, 0.25 mg / mL, 0.125 mg / mL, and 0.0625 mg / mL were included to estimate protein concentration. Gel was stained by covering in water and heating in microwave until solution almost boiled twice, and once with SIMPLYBLUESAFESTAIN. The gel and stain were then shaken for 5 minutes and washed with water for 10 minutes. Concentration was measured as integrated band intensity with IMAGEJ and calibrated to lysozyme controls. Buffer exchange: Buffer exchange to remove imidazole was performed using 3.5K molecular weight cutoff SLIDE0-A-LYZERMINI Dialysis Device with 10 mM sodium phosphate buffer with 4-10 exchanges. Stability Measurement: Purified protein in 10 mM sodium phosphate buffer was diluted to ~0.2 mg / mL in sodium phosphate buffer, and thermal stability and secondary structure were measured via circular dichroism (CD) using a JASCO J-815 CD spectropolarimeter. Thermal stability was measured by monitoring ellipticity at 218 nm as temperature increased from 25 °C to 95 C at 3 °C per minute. Melting temperatures were determined using a two-state unfolding equation and minimizing the sum of squared errors comparing experimental data to model-predicted data (Hackel, B. J., Kapila, A. & Dane Wittrup, K. Picomolar Affinity Fibronectin Domains Engineered Utilizing Loop Length Diversity, Recursive Mutagenesis, and Loop Shuffling. J. Mol. Biol.381, 1238– 1252 (2008)). Spectra were obtained by scanning from 260-190 nM at 25 °C before and after thermal treatment. Secondary structure was predicted from the initial spectra at 25 °C using Beta Structure Selection (BeStSel; Micsonai, A., Moussong, É., Wien, F., Boros, E., Vadászi, H., Murvai, N., Lee, Y. H., Molnár, T., Réfrégiers, M., Goto, Y., Tantos, Á. & Kardos, J. BeStSel: Webserver for secondary structure and fold prediction for protein CD spectroscopy. Nucleic Acids Res.50, W90–W98 (2022)). Affinity Titration: Clonal yeast displaying a scaffold ligand were incubated with His6-tagged target at varying concentrations with rotation at 4 °C for sufficient time to reach 95% of target bound on the lowest concentration sample assuming a konof 2.5×105. Yeast were labeled with mouse anti- V5 antibody (Bio-Rad, Hercules, CA) for 10 minutes followed by Goat anti mouse Alexa647 (Invitrogen, Ipswich, MA) and FITC Anti-6X His tag antibody (Abcam, Cambridge, MA) for 15 minutes. Binding and display were measured via flow cytometry (BD Accuri C6). Affinity curves were constructed based upon the median FITC value of cells that were V5+ (full length protein). KDwas calculated by minimizing the sum of squared errors assuming a 1:1 binding curve and is reported as the average of at least three trials. Specificity measurements were conducted using the same method described, but by testing binding to non-target proteins at 100 nM compared to binding of target at 50 nM. Score Calculation Library Identification: Populations of scaffold variants from binding and developability selections were evaluated to determine the relative frequencies of different scaffold library designs. Sequences were matched to whichever library they emerged from; in the case of the sheet libraries, several sequences had the potential to emerge from multiple libraries, so the frequency of that variant was scaled to the probability of its emergence from the library of interest using the following equation: where pi,j,k is the probability of amino acid i appearing at site j in library k. For cases where the sequence and library both have WT at site j, pi,j=1, for cases where the library has NNK diversification at site j, pi,j= pigiven NNK, and for cases where the library is WT at site j, but the sequence is not, p = pmut, which has been arbitrarily set at 1×10-4to account for random errors during PCR. Sequences are then assigned to libraries based on their probability relative to the other probabilities via the following equation: Developability Scores: Developability scores are calculated as the proportion of a library that appears in the top gate relative to the proportion of that library that appears in the unsorted population. To avoid highly frequent clones dominating the score, the square root of reads was used for this metric. Samples were then normalized by the median of calculated fractions from all libraries. Developability Enrichment Scores: Developability enrichment scores are calculated as the proportion of reads that appear in each gate multiplied by the percentage of that gate, relative to the average. That value for each gate is multiplied by the average score for each gate, and the sum is the developability enrichment score. To avoid highly frequent clones dominating the score, the square root of reads was used for this metric. Samples were then normalized by the median of calculated fractions from all libraries. Evolvability Scores: Evolvability scores are calculated as the proportion of a library that appears in the binder population, relative to the proportion of that library that appears in the naïve population. To avoid highly frequent clones dominating the score, the fourth root of reads was used for this metric.

[0011] Amino Acid Enrichment: Sitewise amino acid enrichment and depletion was analyzed via ScaffoldSeq (Woldring, D. R., Holec, P. V. & Hackel, B. J. ScaffoldSeq: Software for characterization of directed evolution populations. Proteins Struct. Funct. Bioinforma.84, 869–874 (2016)). Statistical Analysis: For all comparisons, one-way ANOVA with a post-hoc Tukey HSD test was performed. P scores of less than 0.05 were considered significant. Experiments were performed in triplicate at a minimum. The complete disclosure of all patents, patent applications, and publicati...

Claims

What is claimed is:

1. A binding protein derived from a parental protein, the parental protein comprising: an N-terminal region; a beta sheet comprising: a first beta-strand coupled to the N-terminal region; a second beta-strand; and a third beta-strand defining the C-terminus of the protein; an alpha-helix; a first loop coupling the first beta-strand and the alpha-helix; a second loop coupling the alpha-helix and the second beta-strand; a third loop coupling the second beta-strand and the third beta-strand; a first solvent-exposed surface comprising a portion of the beta sheet; a second solvent-exposed surface comprising a portion of the alpha-helix; a third solvent-exposed surface comprising at least a portion of the first loop and at least a portion of the third loop; and a binding region comprising at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, or at least a portion of the third solvent-exposed surface; wherein the binding protein differs from the parental protein by at least one residue within the binding region; and wherein the binding protein binds to a target with a dissociation constant of one micromolar or less.

2. The binding protein of claim 1, wherein: the N-terminal region comprises one residue; the first beta-strand comprises five residues; the first loop comprises three residues; the alpha-helix comprises thirteen residues; the second loop comprises two residues; the second beta-strand comprises seven residues; the third loop comprise two residues; andthe third beta-strand comprises seven residues.

3. The binding protein of claim 1 or claim 2, wherein the first solvent-exposed region comprises seven residues.

4. The binding protein of any one of the preceding claims, wherein the first solvent-exposed surface comprises eight residues.

5. The binding protein of any one of the preceding claims, wherein the first solvent-exposed surface comprises nine residues.

6. The binding protein of any one of the preceding claims, wherein the first solvent-exposed surface comprises eleven residues.

7. The binding protein of any claim 6, wherein the first solvent-exposed surface comprises: the N-terminal residue; two residues of the first beta-strand; four residues of the second beta-strand; and four residues of the third beta-strand.

8. The binding protein of any one of claims 1 through 7, wherein the binding protein comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:119) is derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:120) is derived from the parental protein of sequence TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:121) is derived from the parental protein of sequence TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); orXTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:122) is derived from the parental protein of sequence TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

9. The binding protein of claim 5, wherein the first solvent-exposed surface comprises: the N-terminal residue; two residues of the first beta-strand; three residues of the second beta-strand; and three residues of the third beta-strand.

10. The binding protein of any one of claims 1 through 6 or 9, wherein the binding protein comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ NGTYWXVXVX (SEQ ID NO:123) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ ENGKWXVXVX (SEQ ID NO:124) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYXVXVXV KNGTFXVXVX (SEQ ID NO:125) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ KGNKWXVXVX (SEQ ID NO:126) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

11. The binding protein of any one of claims 1 through 6, wherein the binding region comprises: two residues of the first beta-strand; three residues of the second beta-strand; andthree residues of the third beta-strand.

12. The binding protein of any one of claims 1 through 6 or 11, wherein the binding protein comprises a sequence that has 90% or greater sequence identity in residues that are not X of any of the sequences: TTXYXFTDEE EARRAAKEWA RRGYQVXVXQ XGTXWXVXVR (SEQ ID NO:127) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTXIXVDDKE EAKKVAEEWL RRGYTVXIXQ XNGXWXVXVR (SEQ ID NO:128) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYXYXFTDKR AAETAAREWR NRGYDVXVXV XNGXFXVXVR (SEQ ID NO:129) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or TTXYXYDDKQ AAKEAAEEWK KRGYEVXLXQ XGNXWXVXVG (SEQ ID NO:130) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

13. The binding protein of any one of claims 1 through 6, wherein the first solvent-exposed surface comprises: the N-terminal residue; two residues of the first beta-strand; and four residues of the third beta-strand.

14. The binding protein of any one of claims 1 through 6 or 13, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYQVHVTQ NGTXWXVXVX (SEQ ID NO:131) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107);XTXIXVDDKE EAKKVAEEWL RRGYTVTIRQ ENGXWXVXVX (SEQ ID NO:132) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYDVTVTV KNGXFXVXVX (SEQ ID NO:133) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or XTXYXYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNXWXVXVX (SEQ ID NO:134) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

15. The binding protein of any one of claims 1 through 6, wherein the first solvent-exposed surface comprises: the N-terminal residue; two residues of the second beta-strand; and four residues of the second beta-strand.

16. The binding protein of any one of claims 1 through 6 or 15, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTYWEVEVR (SEQ ID NO:135) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGKWHVEVR (SEQ ID NO:136) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGTFTVEVR (SEQ ID NO:137) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNKWQVKVG (SEQ ID NO:138) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110),wherein each X is independently any amino acid.

17. The binding protein of any one of claims 1 through 6, wherein the first solvent-exposed surface comprises: four residues of the second beta-strand; and four residues of the second beta-strand.

18. The binding protein of any one of claims 1 through 6 or 17, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: TTRYRFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:139) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:140) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYTYTFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:141) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or TTTYTYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:142) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

19. The binding protein of any one of claims 1 through 6, wherein the second solvent- exposed surface comprises: one residue of the first loop; and eight residues of the alpha-helix.

20. The binding protein of any one of claims 1 through 6 or 19, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences:TTRYRFTDXX XAXXAAXXWA XXGYQVHVTQ NGTYWEVEVR (SEQ ID NO:111) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVDDXX XAXXVAXXWL XXGYTVTIRQ ENGKWHVEVR (SEQ ID NO:112) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYTYTFTDXX XAXXAAXXWR XXGYDVTVTV KNGTFTVEVR (SEQ ID NO:113) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or TTTYTYDDXX XAXXAAXXWK XXGYEVHLTQ KGNKWQVKVG (SEQ ID NO:114) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

21. The binding protein of any one of claims 1 through 6, wherein the third solvent-exposed surface comprises: three residues of the first loop; one residue of the alpha-helix; two residues of the second beta-strand; two residues of the third loop; and one residue of the third beta-strand.

22. The binding protein of any one of claims 1 through 6 or 21, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: TTRYRFXXXX EARRAAKEWA RRGYQVHVTX XXXXWEVEVR (SEQ ID NO:115) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVXXXX EAKKVAEEWL RRGYTVTIRX XXXXWHVEVR (SEQ ID NO:116) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108);TYTYTFXXXX AAETAAREWR NRGYDVTVTX XXXXFTVEVR (SEQ ID NO:117) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); or TTTYTYXXXX AAKEAAEEWK KRGYEVHLTX XXXXWQVKVG (SEQ ID NO:118) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110), wherein each X is independently any amino acid.

23. The binding protein of any one of claims 1 through 22, wherein the target is B7-H3, CD22, PMSA, IRA, or any combination thereof.

24. The binding protein of claim 23, wherein the target is B7-H3 and the binding protein comprises a sequence that has 90% or greater sequence identity to TTTITVDDVR RAIIVANSWV KRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:143); TTRYRFTDIP HAISAAMLWY RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:144); TTTYTYDDKQ AAKEAAEEWK KRGYWVWLYQ NGNQWFVLVG (SEQ ID NO:145); or TTTITVDDVT RAIKVASGWG RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:146).

25. The binding protein of claim 23, wherein the target is PSMA and the binding protein comprises a sequence that has 90% or greater sequence identity to TTRYRFTDSE YAYDAALYWF RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:147); TTTYTYDDIR KAYRAADYWV FRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:148); or TTTYTYDDGK GAYDAANLWV FRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:149).

26. The binding protein of claim 23, wherein the target is CD22 and the binding protein comprises a sequence that has 90% or greater sequence identity toMTYIAVDDKE EAKKVAEEWL RRGYTVMIGQ LNGHWGVLVR (SEQ ID NO:150); or MTVIIVDDKE EAKKVAEEWL RRGYRVQIGQ FNGDWAVLVA (SEQ ID NO:151).

27. The binding protein of claim 23, wherein the target is IRA and the binding protein comprises a sequence that has 90% or greater sequence identity to HTIYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:152); YTIYEFTDEE EARRAAKEWA RRGYLVHVEQ LGTYWEVEVR (SEQ ID NO:153); LTYYEFTDKE EARRAAKEWA RRGYHVHVFQ LGTYWEVEVR (SEQ ID NO:154); YTMYEFTDEE EARRAAKEWA RRGYYVNVTQ FGTYWEVEVR (SEQ ID NO:155); VTYYEFTDKEE ARRAAKEWA RRGYHVHVFQ LGTYWEVEVR (SEQ ID NO:156); YTLYDFTDEE EARRAAKEWA RRGYTVDVIQ LGTLWVVEVV (SEQ ID NO:157); ATAYWFTDEE EARRAAKEWA RRGYLVFVCQ NGTYWTVSVT (SEQ ID NO:158); YTLYEFTDEE EARRAAKEWA RRGYTVDVIQ LGTLWVVEVV (SEQ ID NO:159); YTLYEFTDEE EARRAAKEWA RRGYRVVVFQ FGTYWEVEVR (SEQ ID NO:160); YTIYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:161); LTYYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:162); YTLYTFTDEE EARRAAKEWA RHGYTVDVIQ LGTLWVVEVV (SEQ ID NO:163);LTYYEFTDEE EARRAAKEWA RRGYSVLVWQ LGTYWEVEVR (SEQ ID NO:164); YTLYTFTDEE EARRAAKEWA RRGYSVDVDQ MGTIWVVEVR (SEQ ID NO:165); YTMYEFTDEE EARRAAKEWA RRGYDVNVTQ FGTYWEVEVR (SEQ ID NO:166); YTLILVDDKE EAKKVAEEWL RRGYWVDICQ VNGVWVVEVS (SEQ ID NO:167); YTLYEFTDEE EARRAAKEWA RRGYKVEVIQ FGTYWEVEVR (SEQ ID NO:168); LTYYEFTDEE EARRAAKEWA RRGYSVGVFQ LGTYWEVEVR (SEQ ID NO:169); YTLITVDDKE EAKKVAEEWL RRGYTVDIVQ FNGCWVVEVV (SEQ ID NO:170); LTYYEFTDKE EARRAAKEWA RRGYSVGVFQ LGTYWEVEVR (SEQ ID NO:171); YTLYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:172); YTLYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:173); YTLYEFTDEE EARRAAKEWA RRGYEVDVVQ FGTYWEVEVR (SEQ ID NO:174); TTRYRFTDEE EARRAAKEWA RRGYSVGVYQ FGTYWFVVVK (SEQ ID NO:175); TTRYAFTDEE EARRAAKEWA RRGYQVGVYQ FGTRWIVAVR (SEQ ID NO:176); HTIYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:177); TTRYRFTDEE EARRAAKEWA RRGYRVGVYQ IGTIWVVVVL (SEQ ID NO:178);TTRYRFTDEE EARRAAKEWA RRGYRVGVYQ LGTNWNVVVK (SEQ ID NO:179); TTRYRFTDEE EARRAAKEWA RRGYQVGVVQ LGTCWLVVVR (SEQ ID NO:180); or a sequence having 90% or greater sequence identity thereto.

28. A screening library comprising a plurality of screening proteins, each screening protein of the plurality of screening proteins comprising a parental protein from any one of claims 1 through 22, wherein each screening protein differs from the parental protein by at least one amino acid residue in the binding region.

29. The screening library of claim 28, wherein each screening protein of the plurality of screening proteins comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:119) is derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:120) is derived from the parental protein of sequence TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:121) is derived from the parental protein of sequence TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:122) is derived from the parental protein of sequence TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ NGTYWXVXVX (SEQ ID NO:123) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ ENGKWXVXVX (SEQ ID NO:124) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108);XYXYXFTDKR AAETAAREWR NRGYXVXVXV KNGTFXVXVX (SEQ ID NO:125) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ KGNKWXVXVX (SEQ ID NO:126) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); TTXYXFTDEE EARRAAKEWA RRGYQVXVXQ XGTXWXVXVR (SEQ ID NO:127) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTXIXVDDKE EAKKVAEEWL RRGYTVXIXQ XNGXWXVXVR (SEQ ID NO:128) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYXYXFTDKR AAETAAREWR NRGYDVXVXV XNGXFXVXVR (SEQ ID NO:129) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); TTXYXYDDKQ AAKEAAEEWK KRGYEVXLXQ XGNXWXVXVG (SEQ ID NO:130) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); XTXYXFTDEE EARRAAKEWA RRGYQVHVTQ NGTXWXVXVX (SEQ ID NO:131) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYTVTIRQ ENGXWXVXVX (SEQ ID NO:132) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYDVTVTV KNGXFXVXVX (SEQ ID NO:133) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); XTXYXYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNXWXVXVX (SEQ ID NO:134) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110)XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTYWEVEVR (SEQ ID NO:135) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGKWHVEVR (SEQ ID NO:136) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGTFTVEVR (SEQ ID NO:137) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNKWQVKVG (SEQ ID NO:138) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); TTRYRFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:139) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:140) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYTYTFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:141) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); TTTYTYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:142) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); TTRYRFTDXX XAXXAAXXWA XXGYQVHVTQ NGTYWEVEVR (SEQ ID NO:111) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVDDXX XAXXVAXXWL XXGYTVTIRQ ENGKWHVEVR (SEQ ID NO:112) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108);TYTYTFTDXX XAXXAAXXWR XXGYDVTVTV KNGTFTVEVR (SEQ ID NO:113) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); TTTYTYDDXX XAXXAAXXWK XXGYEVHLTQ KGNKWQVKVG (SEQ ID NO:114) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); TTRYRFXXXX EARRAAKEWA RRGYQVHVTX XXXXWEVEVR (SEQ ID NO:115) derived from the parental protein of the sequence TTRYRFTDEE EARRAAKEWA RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:107); TTTITVXXXX EAKKVAEEWL RRGYTVTIRX XXXXWHVEVR (SEQ ID NO:116) derived from the parental protein of TTTITVDDKE EAKKVAEEWL RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:108); TYTYTFXXXX AAETAAREWR NRGYDVTVTX XXXXFTVEVR (SEQ ID NO:117) derived from the parental protein of TYTYTFTDKR AAETAAREWR NRGYDVTVTV KNGTFTVEVR (SEQ ID NO:3); TTTYTYXXXX AAKEAAEEWK KRGYEVHLTX XXXXWQVKVG (SEQ ID NO:118) derived from the parental protein of TTTYTYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:110); or any combination thereof, wherein each X is independently any amino acid.

30. A screening method comprising: forming a library comprising a plurality of screening proteins of claim 28 or 29; exposing the library to a target; sorting the library for screening proteins that bind to the target; and determining the amino acid sequence of at least one screening protein that bound to the target with a dissociation constant of one micromolar or less.

31. A binding protein derived from a parental protein, the parental protein comprising: a beta-sheet comprising: a first beta-strand defining the N-terminus of the binding protein; a second beta-strand;a third beta-strand; and a fourth beta-strand; an alpha-helix; a C-terminal portion defining the C-terminus of the binding protein, the C- terminal portion coupled to the fourth beta-strand; a first loop coupling the first beta-strand and the second beta-strand; a second loop coupling the second beta-strand and the alpha-helix; a third loop coupling the alpha-helix and the third beta-strand; a fourth loop coupling the third beta-strand and the fourth beta-strand; a first solvent-exposed surface comprising a portion of the alpha-helix; a second solvent-exposed surface comprising a portion of the beta-sheet; a third solvent-exposed surface comprising a portion of the first loop and a portion of the third loop; and a binding region comprising at least a portion of the first solvent-exposed surface, at least a portion of the second solvent-exposed surface, or at least a portion of the third solvent-exposed surface; wherein the binding protein differs from the parental protein by at least residue within the binding region; and wherein the binding protein binds to a target with a dissociation constant of one micromolar or less.

32. The binding protein of claim 31, wherein: the first beta-strand of the parental protein comprises three or four residues; the first loop of the parental protein comprises four amino acid residues; the second beta-strand of the parental protein comprise three or four residues; the second loop of the parental protein comprises two or three residues; the alpha-helix of the parental protein comprises fifteen residues; the third loop of the alpha-helix comprises three residues; the third beta-strand of the parental protein comprises four residues; the fourth loop of the parental protein comprise two residues; and the fourth beta-strand of the parental protein comprises four residues.

33. The binding protein of claim 31 or 32, wherein the first solvent-exposed surface comprises twelve residues.

34. The binding protein of any of claims 31 to 33, wherein the second solvent-exposed surface comprises ten residues.

35. The binding protein of any of claims 31 to 34, wherein the third solvent-exposed surface comprises eleven residues.

36. The binding protein of any one of claims 31 to 35, wherein the binding region comprises at least a portion of the first solvent-exposed region and the first solvent-exposed region comprises: two amino acid residues of the first beta-strand; two amino acid residues of the second beta-strand; and one amino acid residues of the first loop.

37. The binding protein of claim 36, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:79) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:80) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TXVXVGXVXY XFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:81) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:82) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:83) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); orTXVXIGXVXY XFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:84) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71), wherein each X is independently any amino acid.

38. The binding protein of any one of claims 31 to 35, wherein the binding region comprises at least a portion of the first solvent-exposed region and the second solvent-exposed region comprises: one amino acid residue of the third loop; two amino acid residues of the third beta-strand; one amino acid reside of the fourth loop; two amino acid residues of the fourth beta-strand; and the C-terminal amino acid.

39. The binding protein of claim 38, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:85) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:86) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVGNVTY HFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:87) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:88) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:89) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); orTTVHIGNVTY HFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:90) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71), wherein each X is independently any amino acid.

40. The binding protein of any one of claims 31 to 35, wherein the binding region comprises at least a portion of the first solvent-exposed surface wherein the second solvent- exposed surface comprises: two amino acid residues of the first beta-strand; one amino acid residue of the first loop; two amino acid residues of the second beta-strand; one amino acid residue of the third loop; two amino acid residues of the third beta-strand; one amino acid residue of the fourth loop; two amino acid residues of the fourth beta-strand; and the C-terminal residue.

41. The binding protein of any one of claims 31 to 35 or 40, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:91) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:92) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TXVXVGXVXY XFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:93) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:94) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69);VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:95) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); or TXVXIGXVXY XFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:96) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71), wherein each X is independently any amino acid.

42. The binding protein of any one of claims 31 to 35, wherein the binding region comprises at least a portion of the second solvent-exposed region and the second solvent- exposed region comprises twelve amino acid residues of the alpha-helix.

43. The binding protein of claim 42, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: ATVHVNGVTY HFDNPXXAXX XAXXXAXXXN LRIEVHGNTI RVE (SEQ ID NO:73) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVNGVQY DFDNPXXAXX XAXXXAXXXN LRIEFHGNTI HIE (SEQ ID NO:74) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVGNVTY HFPNPXXAXX XAXXXAXXXN LKIEVHGDTI RVE (SEQ ID NO:75) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVNGVTY HFDNPXXAXX XVXXXAXXXGL TYRVEGNTW HIE (SEQ ID NO:76) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VTVDVNGVKY TFDEPXXAXX XAXXXAXXXN LRVEIHGNTI RVE (SEQ ID NO:77) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); or TTVHIGNVTY HFDNPXXAXX XAXXXAXXXG LRVEMDNGNF KVE (SEQ ID NO:78) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71),wherein each X is independently any amino acid.

44. The binding protein of any one of claims 31 to 35, wherein the binding region comprises at least a portion of the third solvent-exposed surface wherein the third solvent- exposed surface comprises: three residues of the first loop; one residue of the alpha-helix; two amino acid residues of the third loop; and the C-terminal residue.

45. The binding protein of any one of claims 31 to 35 or 44, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: ATVHVXXXTY HFDNPEEAKK FAKKVAKKXX XRIEVHGNTI RVX (SEQ ID NO:97) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVXXXQY DFDNPEEAVK FALKVAKKXX XRIEFHGNTI HIX (SEQ ID NO:98) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVXXXTY HFPNPEEAYK FALRVAREXX XKIEVHGDTI RVX (SEQ ID NO:99) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVXXXTY HFDNPEEAKK FVEKVAKEXX XTYRVEGNTW HIX (SEQ ID NO:100) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VTVDVXXXKY TFDEPEQAKK FAKEMAEKXX XRVEIHGNTI RVX (SEQ ID NO:101) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); or TTVHIXXXTY HFDNPREAEE FAKKVAKKXX XRVEMDNGNF KVX (SEQ ID NO:102) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71), wherein each X is independently any amino acid.

46. The binding protein of any one of claims 31 to 46, wherein the target is CTLA4, VEGF, PD-1, or IGF1R.

47. The binding protein of claim 46, wherein the target is VEGF and the binding protein comprises a sequence that has 90% or greater sequence identity to: VLVPVNGVVY RFDEPEQAKK FAKEMAEKLN LVVLIEGRDI AVV (SEQ ID NO:103), VLVVVNGVGY GFDEPEQAKK FAKEMAEKLN LAVRISGSTI IVF (SEQ ID NO:104), VWVKVNFVMY CFDEPEQAKK FAKEMAEKLN LIVVIDGCEI IVV (SEQ ID NO:105), VWVWVNGVKY TFDEPEQAKK FAKEMAEKLN LPVLIVGSII FVG (SEQ ID NO:106), or a sequence having 90% or greater sequence identity thereto.

48. A screening library comprising a plurality of screening proteins, each screening protein of the plurality of screening proteins comprising a parental protein from any one of claims 31 through 47, wherein each screening protein differs from the parental protein by at least one amino acid residue in the binding region.

49. The screening library of claim 48, wherein each screening protein of the plurality of screening proteins comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:79) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:80) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TXVXVGXVXY XFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:81) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68);AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:82) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:83) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); TXVXIGXVXY XFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:84) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71); ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:85) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:86) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVGNVTY HFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:87) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:88) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:89) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:90) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71); AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:91) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72);AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:92) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TXVXVGXVXY XFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:93) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:94) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:95) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); TXVXIGXVXY XFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:96) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71); ATVHVNGVTY HFDNPXXAXX XAXXXAXXXN LRIEVHGNTI RVE (SEQ ID NO:73) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVNGVQY DFDNPXXAXX XAXXXAXXXN LRIEFHGNTI HIE (SEQ ID NO:74) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVGNVTY HFPNPXXAXX XAXXXAXXXN LKIEVHGDTI RVE (SEQ ID NO:75) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVNGVTY HFDNPXXAXX XVXXXAXXXGL TYRVEGNTW HIE (SEQ ID NO:76) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69);VTVDVNGVKY TFDEPXXAXX XAXXXAXXXN LRVEIHGNTI RVE (SEQ ID NO:77) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); TTVHIGNVTY HFDNPXXAXX XAXXXAXXXG LRVEMDNGNF KVE (SEQ ID NO:78) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71); ATVHVXXXTY HFDNPEEAKK FAKKVAKKXX XRIEVHGNTI RVX (SEQ ID NO:97) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:72); ATVHVXXXQY DFDNPEEAVK FALKVAKKXX XRIEFHGNTI HIX (SEQ ID NO:98) derived from parental protein comprising the sequence ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:67); TTVHVXXXTY HFPNPEEAYK FALRVAREXX XKIEVHGDTI RVX (SEQ ID NO:99) derived from parental protein comprising the sequence TTVHVGNVTY HFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:68); ATVHVXXXTY HFDNPEEAKK FVEKVAKEXX XTYRVEGNTW HIX (SEQ ID NO:100) derived from parental protein comprising the sequence ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:69); VTVDVXXXKY TFDEPEQAKK FAKEMAEKXX XRVEIHGNTI RVX (SEQ ID NO:101) derived from parental protein comprising the sequence VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:70); TTVHIXXXTY HFDNPREAEE FAKKVAKKXX XRVEMDNGNF KVX (SEQ ID NO:102) derived from the parental protein comprising the sequence TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:71); or any combination thereof, wherein each X is independently any amino acid.

50. A screening method comprising: forming a library comprising a plurality of screening proteins of claim 48 or 49; exposing the library to a target;sorting the library for screening proteins that bind to the target; and determining the amino acid sequence of at least one screening protein that bound to the target with a dissociation constant of one micromolar or less.

51. A binding protein derived from a parental protein, the parental protein comprising: an N-terminal region defining the N-terminus of the binding protein; a first alpha-helix coupled to the N-terminal region; a second alpha-helix; a third alpha-helix; a C-terminal region defining the C-terminus of the binding protein coupled to the third alpha-helix; a first loop coupling the first alpha-helix and the second alpha-helix; a second loop coupling the second alpha-helix and the third alpha-helix; a first solvent-exposed surface comprising a first portion of the first alpha-helix; a second solvent-exposed surface comprising a first portion of the second alpha- helix; a third solvent-exposed surface comprising a second portion of the second alpha- helix and a first portion of the third alpha-helix; a fourth solvent-exposed surface comprising a second portion of the first alpha- helix and a third portion of the second alpha-helix; a binding region comprising at least a portion of the first solvent--exposed surface, at least a portion of the second solvent-exposed surface, at least a portion of the third solvent-exposed surface, or at least a portion of the fourth solvent-exposed surface; wherein the binding protein differs from the parental protein by at least one residue within the binding region; and wherein the binding protein binds to a target with a dissociation constant of one micromolar or less.

52. The binding protein of claim 51, wherein: the first alpha-helix comprises twelve amino acid residues; the second alpha-helix comprises elven amino acid residues;the third alpha-helix comprises ten amino acid residues; the first loop comprise four amino acid residues; the second loop comprises four amino acid residues; the N-terminal region comprises one amino acid residues; and the C-terminal region comprises one amino acid residue.

53. The binding protein of claim 51 or 52, wherein the first solvent-exposed surface comprises nine residues.

54. The binding protein of any of claims 51 to 53, wherein the second solvent-exposed surface comprises eight residues.

55. The binding protein of any of claims 51 to 54, wherein the third solvent-exposed surface comprises eight residues.

56. The binding protein of any of claims 51 to 55, wherein the fourth solvent-exposed surface comprises eight residues.

57. The binding protein of any of claims 51 to 57, wherein the binding region comprises at least a portion of the first solvent-exposed surface.

58. The binding protein of claim 57, wherein the binding region comprises: eight amino acid residues of the first alpha-helix; and one amino acid residue of the first loop.

59. The binding protein of claim 58, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DXXAEXXVXX LXXXGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:7) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DXXELXXEXX KXXXKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:8) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1);DXXVEXXVXX LXXXGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:9) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DXXLEXXVXX LXXXGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:10) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KXXAEXXVXX LXXXGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:11) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); or DXXAKXXVXX LXXXGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:12) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5), wherein each X is independently any amino acid.

60. The binding protein of any one of any of claims 51 to 57, wherein the binding region comprises at least a portion of the second solvent-exposed surface.

61. The binding protein of claim 60, wherein the binding region comprises: one amino acid residue of the first loop; and seven amino acid residues of the second alpha-helix.

62. The binding protein of claim 61, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DEEAERIVRE LKRRGVXXXX IXXILXXAGL SDEQVKKLIR RVL (SEQ ID NO:13) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KALRKGXXXX VXXIAXXIGI DDRQVEKLLK DIL (SEQ ID NO:14) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1);DEEVERIVRE LKKRGIXXXX IXXILXXNGF DEKEVREIVE KVA (SEQ ID NO:15) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LKRNGVXXXX IXXWLXXAGL SPDQVKEVID RVL (SEQ ID NO:16) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KEEAEKIVRE LLRRGVXXXX IXXILXXAGL SDEDVKRLIR RVK (SEQ ID NO:17) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); or DEEAKKLVRK LIRNGVXXXX LXXALXXLGF SPEQVKKIVR DVK (SEQ ID NO:18) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5), wherein each X is independently any amino acid.

63. The binding protein of any of claims 51 to 57, wherein the binding region comprises at least a portion of the third solvent-exposed surface.

64. The binding protein of claim 63, wherein the binding region comprises: four amino acid residues of the second alpha-helix; and four amino acid residues of the third alpha-helix.

65. The binding protein of claim 64, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DEEAERIVRE LKRRGVSXXE IXEILXRAGL SDXQVXXLIX RVL (SEQ ID NO:19) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KALRKGDXXK VXRIAXRIGI DDXQVXXLLX DIL (SEQ ID NO:20) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1);DEEVERIVRE LKKRGISXXQ IXEILXKNGF DEXEVXXIVX KVA (SEQ ID NO:21) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LKRNGVSXXE IXEWLXRAGL SPXQVXXVIX RVL (SEQ ID NO:22) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KEEAEKIVRE LLRRGVSXXE IXDILXKAGL SDXDVXXLIX RVK (SEQ ID NO:23) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); or DEEAKKLVRK LIRNGVSXXQ LXRALXRLG FSPXQVXXIVX DVK (SEQ ID NO:24) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5), wherein each X is independently any amino acid.

66. The binding protein of any of claims 51 to 57, wherein the binding region comprises at least a portion of the fourth solvent-exposed surface.

67. The binding protein of claim 66, wherein the binding region comprises: two amino acid residues of the first alpha-helix; one amino acid residue of the first loop; and four amino acid residues of the second alpha-helix.

68. The binding protein of claim 67, wherein the binding protein comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DEEAERIVRE LXXRGVXXXX IXEILKRAGL SDEQVKKLIR RVX (SEQ ID NO:25) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KXXRKGXXXX VXRIARRIGI DDRQVEKLLK DIX (SEQ ID NO:26) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1);DEEVERIVRE LXXRGIXXXX IXEILKKNGF DEKEVREIVE KVX (SEQ ID NO:27) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LXXNGVXXXX IXEWLRRAGL SPDQVKEVID RVX (SEQ ID NO:28) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KEEAEKIVRE LXXRGVXXXX IXDILKKAGL SDEDVKRLIR RVX (SEQ ID NO:29) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); or DEEAKKLVRK LXXNGVXXXX LXRALKRLGF SPEQVKKIVR DVX (SEQ ID NO:30) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5), wherein each X is independently any amino acid.

69. The binding protein of any one of claims 51 through 68, wherein the target is PD-1, CTLA-4, VEGF, IGF1R, or any combination thereof.

70. The binding protein of claim 69, wherein the target is VEGF and the binding protein comprises a sequence that has 90% or greater sequence identity to DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVT (SEQ ID NO:31); DEEAKKLVRK LIRNGVCCTR LLWALITLGF SPEQVKKIVR DVK (SEQ ID NO:32), DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVG (SEQ ID NO:33); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR EVR (SEQ ID NO:34); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:35); DEEAKKLVRE LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:36);DEEAKKLVRK LIRNGVSDNG LWVELASLGF SPEQVKKIVR DVR (SEQ ID NO:37); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVNKIVR DVR (SEQ ID NO:38); YEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:39); DEEAKKLVRK LIRNGVSDNG LWVALASLSF SPEQVKKIVR DVR (SEQ ID NO:40); DEEAKKLVRK LIRNGVSDNG LWVALAPLGF SPEQVKKIVR DVR (SEQ ID NO:41); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVW DVR (SEQ ID NO:42); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR YVR (SEQ ID NO:43); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR(SEQ ID NO:44); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQIKKIVR DVR (SEQ ID NO:45); DEEAKKLVRK LIRNGVSDNG LWVAPASLGF SPEQVKKIVR DVR (SEQ ID NO:46); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DFR (SEQ ID NO:47); DEDAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:48); DEEAKKLVRK LIRNCVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:49); DEEAKKLVCK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:50); NEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:51);DERLERRVEE LKRNGVTDHG ISLWLLGAGL SPDQVKEVID RVL (SEQ ID NO:52); DERLERRVEE LKRNGVTDHG IVLWLLGAGL SPDQVKEVID RVL (SEQ ID NO:53); or a sequence having 90% or greater identity thereto.

71. A screening library comprising a plurality of screening proteins, each screening protein of the plurality of screening proteins comprising a parental protein from any one of claims 51 through 68, wherein each screening protein differs from the parental protein by at least one amino acid residue in the binding region.

72. The screening library of claim 71, wherein each screening protein of the plurality of screening proteins comprises a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DXXAEXXVXX LXXXGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:7) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DXXELXXEXX KXXXKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:8) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1); DXXVEXXVXX LXXXGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:9) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DXXLEXXVXX LXXXGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:10) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KXXAEXXVXX LXXXGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:11) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); DXXAKXXVXX LXXXGVSDEQ LERALKRLGF SPEQVKKIVR DVK(SEQ ID NO:12) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5)DEEAERIVRE LKRRGVXXXX IXXILXXAGL SDEQVKKLIR RVL (SEQ ID NO:13) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KALRKGXXXX VXXIAXXIGI DDRQVEKLLK DIL (SEQ ID NO:14) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1); DEEVERIVRE LKKRGIXXXX IXXILXXNGF DEKEVREIVE KVA (SEQ ID NO:15) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LKRNGVXXXX IXXWLXXAGL SPDQVKEVID RVL (SEQ ID NO:16) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KEEAEKIVRE LLRRGVXXXX IXXILXXAGL SDEDVKRLIR RVK (SEQ ID NO:17) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); DEEAKKLVRK LIRNGVXXXX LXXALXXLGF SPEQVKKIVR DVK (SEQ ID NO:18) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5); DEEAERIVRE LKRRGVSXXE IXEILXRAGL SDXQVXXLIX RVL (SEQ ID NO:19) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KALRKGDXXK VXRIAXRIGI DDXQVXXLLX DIL (SEQ ID NO:20) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1); DEEVERIVRE LKKRGISXXQ IXEILXKNGF DEXEVXXIVX KVA (SEQ ID NO:21) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LKRNGVSXXE IXEWLXRAGL SPXQVXXVIX RVL (SEQ ID NO:22) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3);KEEAEKIVRE LLRRGVSXXE IXDILXKAGL SDXDVXXLIX RVK (SEQ ID NO:23) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); DEEAKKLVRK LIRNGVSXXQ LXRALXRLG FSPXQVXXIVX DVK (SEQ ID NO:24) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5); DEEAERIVRE LXXRGVXXXX IXEILKRAGL SDEQVKKLIR RVX (SEQ ID NO:25) derived from the parental protein comprising the sequence of DEEAERIVRE LKRRGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:6); DEEELRRELE KXXRKGXXXX VXRIARRIGI DDRQVEKLLK DIX (SEQ ID NO:26) derived from the parental protein comprising the sequence of DEEELRRELE KALRKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:1); DEEVERIVRE LXXRGIXXXX IXEILKKNGF DEKEVREIVE KVX (SEQ ID NO:27) derived from the parental protein comprising the sequence of DEEVERIVRE LKKRGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:2); DERLERRVEE LXXNGVXXXX IXEWLRRAGL SPDQVKEVID RVX (SEQ ID NO:28) derived from the parental protein comprising the sequence of DERLERRVEE LKRNGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:3); KEEAEKIVRE LXXRGVXXXX IXDILKKAGL SDEDVKRLIR RVX (SEQ ID NO:29) derived from the parental protein comprising the sequence of KEEAEKIVRE LLRRGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:4); DEEAKKLVRK LXXNGVXXXX LXRALKRLGF SPEQVKKIVR DVX (SEQ ID NO:30) derived from the parental protein comprising the sequence of DEEAKKLVRK LIRNGVSDEQ LERALKRLGF SPEQVKKIVR DVK (SEQ ID NO:5); or any combination thereof, wherein each X is independently any amino acid.

73. A screening method comprising: forming a library comprising a plurality of screening proteins of claim 71 or 72; exposing the library to a target;sorting the library for screening proteins that bind to the target; and determining the amino acid sequence of at least one screening protein that bound to the target with a dissociation constant of one micromolar or less.

74. A binding protein comprising a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:119); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:120); XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:121); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:122); XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ NGTYWXVXVX (SEQ ID NO:123); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ ENGKWXVXVX (SEQ ID NO:124); XYXYXFTDKR AAETAAREWR NRGYXVXVXV KNGTFXVXVX (SEQ ID NO:125); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ KGNKWXVXVX (SEQ ID NO:126); TTXYXFTDEE EARRAAKEWA RRGYQVXVXQ XGTXWXVXVR (SEQ ID NO:127); TTXIXVDDKE EAKKVAEEWL RRGYTVXIXQ XNGXWXVXVR (SEQ ID NO:128); TYXYXFTDKR AAETAAREWR NRGYDVXVXV XNGXFXVXVR (SEQ ID NO:129); TTXYXYDDKQ AAKEAAEEWK KRGYEVXLXQ XGNXWXVXVG (SEQ ID NO:130);XTXYXFTDEE EARRAAKEWA RRGYQVHVTQ NGTXWXVXVX (SEQ ID NO:131); XTXIXVDDKE EAKKVAEEWL RRGYTVTIRQ ENGXWXVXVX (SEQ ID NO:132); XYXYXFTDKR AAETAAREWR NRGYDVTVTV KNGXFXVXVX (SEQ ID NO:133); XTXYXYDDKQ AAKEAAEEWK KRGYEVHLTQ KGNXWXVXVX (SEQ ID NO:134); XTXYXFTDEE EARRAAKEWA RRGYXVXVXQ XGTYWEVEVR (SEQ ID NO:135); XTXIXVDDKE EAKKVAEEWL RRGYXVXIXQ XNGKWHVEVR (SEQ ID NO:136) XYXYXFTDKR AAETAAREWR NRGYXVXVXV XNGTFTVEVR (SEQ ID NO:137); XTXYXYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNKWQVKVG (SEQ ID NO:138); TTRYRFTDEE EARRAAKEWA RRGYXVXVXQ XGTXWXVXVX (SEQ ID NO:139); TTTITVDDKE EAKKVAEEWL RRGYXVXIXQ XNGXWXVXVX (SEQ ID NO:140) TYTYTFTDKR AAETAAREWR NRGYXVXVXV XNGXFXVXVX (SEQ ID NO:141); or TTTYTYDDKQ AAKEAAEEWK KRGYXVXLXQ XGNXWXVXVX (SEQ ID NO:142), wherein each X is independently any amino acid.

75. A binding protein comprising a sequence that has 90% or greater sequence identity to TTTITVDDVR RAIIVANSWV KRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:143);TTRYRFTDIP HAISAAMLWY RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:144); TTTYTYDDKQ AAKEAAEEWK KRGYWVWLYQ NGNQWFVLVG (SEQ ID NO:145); or TTTITVDDVT RAIKVASGWG RRGYTVTIRQ ENGKWHVEVR (SEQ ID NO:146).

76. A binding protein comprising a sequence that has 90% or greater sequence identity to TTRYRFTDSE YAYDAALYWF RRGYQVHVTQ NGTYWEVEVR (SEQ ID NO:147); TTTYTYDDIR KAYRAADYWV FRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:148); or TTTYTYDDGK GAYDAANLWV FRGYEVHLTQ KGNKWQVKVG (SEQ ID NO:149).

77. A binding protein comprising a sequence that has 90% or greater sequence identity to MTYIAVDDKE EAKKVAEEWL RRGYTVMIGQ LNGHWGVLVR (SEQ ID NO:150); or MTVIIVDDKE EAKKVAEEWL RRGYRVQIGQ FNGDWAVLVA (SEQ ID NO:151).

78. A binding protein comprising a sequence that has 90% or greater sequence identity to HTIYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:152); YTIYEFTDEE EARRAAKEWA RRGYLVHVEQ LGTYWEVEVR (SEQ ID NO:153); LTYYEFTDKE EARRAAKEWA RRGYHVHVFQ LGTYWEVEVR (SEQ ID NO:154;YTMYEFTDEE EARRAAKEWA RRGYYVNVTQ FGTYWEVEVR (SEQ ID NO:155); VTYYEFTDKEE ARRAAKEWA RRGYHVHVFQ LGTYWEVEVR (SEQ ID NO:156); YTLYDFTDEE EARRAAKEWA RRGYTVDVIQ LGTLWVVEVV (SEQ ID NO:157); ATAYWFTDEE EARRAAKEWA RRGYLVFVCQ NGTYWTVSVT (SEQ ID NO:158); YTLYEFTDEE EARRAAKEWA RRGYTVDVIQ LGTLWVVEVV (SEQ ID NO:159); YTLYEFTDEE EARRAAKEWA RRGYRVVVFQ FGTYWEVEVR (SEQ ID NO:160); YTIYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:161); LTYYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:162); YTLYTFTDEE EARRAAKEWA RHGYTVDVIQ LGTLWVVEVV (SEQ ID NO:163); LTYYEFTDEE EARRAAKEWA RRGYSVLVWQ LGTYWEVEVR (SEQ ID NO:164); YTLYTFTDEE EARRAAKEWA RRGYSVDVDQ MGTIWVVEVR (SEQ ID NO:165); YTMYEFTDEE EARRAAKEWA RRGYDVNVTQ FGTYWEVEVR (SEQ ID NO:166); YTLILVDDKE EAKKVAEEWL RRGYWVDICQ VNGVWVVEVS (SEQ ID NO:167); YTLYEFTDEE EARRAAKEWA RRGYKVEVIQ FGTYWEVEVR (SEQ ID NO:168); LTYYEFTDEE EARRAAKEWA RRGYSVGVFQ LGTYWEVEVR (SEQ ID NO:169);YTLITVDDKE EAKKVAEEWL RRGYTVDIVQ FNGCWVVEVV (SEQ ID NO:170); LTYYEFTDKE EARRAAKEWA RRGYSVGVFQ LGTYWEVEVR (SEQ ID NO:171); YTLYEFTDEE EARRAAKEWA RRGYMVDVTQ FGTYWEVEVR (SEQ ID NO:172); YTLYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:173); YTLYEFTDEE EARRAAKEWA RRGYEVDVVQ FGTYWEVEVR (SEQ ID NO:174); TTRYRFTDEE EARRAAKEWA RRGYSVGVYQ FGTYWFVVVK (SEQ ID NO:175); TTRYAFTDEE EARRAAKEWA RRGYQVGVYQ FGTRWIVAVR (SEQ ID NO:176); HTIYEFTDEE EARRAAKEWA RRGYFVNVFQ LGTYWEVEVR (SEQ ID NO:177); TTRYRFTDEE EARRAAKEWA RRGYRVGVYQ IGTIWVVVVL (SEQ ID NO:178); TTRYRFTDEE EARRAAKEWA RRGYRVGVYQ LGTNWNVVVK (SEQ ID NO:179); or TTRYRFTDEE EARRAAKEWA RRGYQVGVVQ LGTCWLVVVR (SEQ ID NO:180).

79. A binding protein comprising a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LRIEVHGNTI RVE (SEQ ID NO:79); AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LRIEFHGNTI HIE (SEQ ID NO:80); TXVXVGXVXY XFPNPEEAYK FALRVARELN LKIEVHGDTI RVE (SEQ ID NO:81);AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LTYRVEGNTW HIE (SEQ ID NO:82); VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LRVEIHGNTI RVE (SEQ ID NO:83); TXVXIGXVXY XFDNPREAEE FAKKVAKKLG LRVEMDNGNF KVE (SEQ ID NO:84); ATVHVNGVTY HFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:85); ATVHVNGVQY DFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:86); TTVHVGNVTY HFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:87); ATVHVNGVTY HFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:88); VTVDVNGVKY TFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:89); TTVHIGNVTY HFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:90); AXVXVNXVXY XFDNPEEAKK FAKKVAKKLN LXIXVXGXXI XVX (SEQ ID NO:91); AXVXVNXVXY XFDNPEEAVK FALKVAKKLN LXIXFXGXXI XIX (SEQ ID NO:92); TXVXVGXVXY XFPNPEEAYK FALRVARELN LXIXVXGXXI XVX (SEQ ID NO:93); AXVXVNXVXY XFDNPEEAKK FVEKVAKELG LXYXVXGXXW XIX (SEQ ID NO:94); VXVXVNXVXY XFDEPEQAKK FAKEMAEKLN LXVXIXGXXI XVX (SEQ ID NO:95); TXVXIGXVXY XFDNPREAEE FAKKVAKKLG LXVXMXNXXF XVX (SEQ ID NO:96);ATVHVNGVTY HFDNPXXAXX XAXXXAXXXN LRIEVHGNTI RVE (SEQ ID NO:73); ATVHVNGVQY DFDNPXXAXX XAXXXAXXXN LRIEFHGNTI HIE (SEQ ID NO:74); TTVHVGNVTY HFPNPXXAXX XAXXXAXXXN LKIEVHGDTI RVE (SEQ ID NO:75); ATVHVNGVTY HFDNPXXAXX XVXXXAXXXGL TYRVEGNTW HIE (SEQ ID NO:76); VTVDVNGVKY TFDEPXXAXX XAXXXAXXXN LRVEIHGNTI RVE (SEQ ID NO:77); TTVHIGNVTY HFDNPXXAXX XAXXXAXXXG LRVEMDNGNF KVE (SEQ ID NO:78); ATVHVXXXTY HFDNPEEAKK FAKKVAKKXX XRIEVHGNTI RVX (SEQ ID NO:97); ATVHVXXXQY DFDNPEEAVK FALKVAKKXX XRIEFHGNTI HIX (SEQ ID NO:98); TTVHVXXXTY HFPNPEEAYK FALRVAREXX XKIEVHGDTI RVX (SEQ ID NO:99); ATVHVXXXTY HFDNPEEAKK FVEKVAKEXX XTYRVEGNTW HIX (SEQ ID NO:100); VTVDVXXXKY TFDEPEQAKK FAKEMAEKXX XRVEIHGNTI RVX (SEQ ID NO:101); or TTVHIXXXTY HFDNPREAEE FAKKVAKKXX XRVEMDNGNF KVX (SEQ ID NO:102), wherein each X is independently any amino acid.

80. A binding protein comprising a sequence that has 90% or greater sequence identity to VLVPVNGVVY RFDEPEQAKK FAKEMAEKLN LVVLIEGRDI AVV (SEQ ID NO:103);VLVVVNGVGY GFDEPEQAKK FAKEMAEKLN LAVRISGSTI IVF (SEQ ID NO:104); VWVKVNFVMY CFDEPEQAKK FAKEMAEKLN LIVVIDGCEI IVV (SEQ ID NO:105); or VWVWVNGVKY TFDEPEQAKK FAKEMAEKLN LPVLIVGSII FVG (SEQ ID NO:106).

81. A binding protein comprising a sequence that has 90% or greater sequence identity to residues other than X of any of the sequences: DXXAEXXVXX LXXXGVSDEE IEEILKRAGL SDEQVKKLIR RVL (SEQ ID NO:7); DXXELXXEXX KXXXKGDEDK VRRIARRIGI DDRQVEKLLK DIL (SEQ ID NO:8); DXXVEXXVXX LXXXGISKDQ IVEILKKNGF DEKEVREIVE KVA (SEQ ID NO:9); DXXLEXXVXX LXXXGVSDEE IKEWLRRAGL SPDQVKEVID RVL (SEQ ID NO:10); KXXAEXXVXX LXXXGVSDEE IEDILKKAGL SDEDVKRLIR RVK (SEQ ID NO:11); DXXAKXXVXX LXXXGVSDEQ LERALKRLGF SPEQVKKIVR DVK(SEQ ID NO:12); DEEAERIVRE LKRRGVXXXX IXXILXXAGL SDEQVKKLIR RVL (SEQ ID NO:13); DEEELRRELE KALRKGXXXX VXXIAXXIGI DDRQVEKLLK DIL (SEQ ID NO:14); DEEVERIVRE LKKRGIXXXX IXXILXXNGF DEKEVREIVE KVA (SEQ ID NO:15); DERLERRVEE LKRNGVXXXX IXXWLXXAGL SPDQVKEVID RVL (SEQ ID NO:16); KEEAEKIVRE LLRRGVXXXX IXXILXXAGL SDEDVKRLIR RVK (SEQ ID NO:17);DEEAKKLVRK LIRNGVXXXX LXXALXXLGF SPEQVKKIVR DVK (SEQ ID NO:18); DEEAERIVRE LKRRGVSXXE IXEILXRAGL SDXQVXXLIX RVL (SEQ ID NO:19); DEEELRRELE KALRKGDXXK VXRIAXRIGI DDXQVXXLLX DIL (SEQ ID NO:20); DEEVERIVRE LKKRGISXXQ IXEILXKNGF DEXEVXXIVX KVA (SEQ ID NO:21); DERLERRVEE LKRNGVSXXE IXEWLXRAGL SPXQVXXVIX RVL (SEQ ID NO:22); KEEAEKIVRE LLRRGVSXXE IXDILXKAGL SDXDVXXLIX RVK (SEQ ID NO:23); DEEAKKLVRK LIRNGVSXXQ LXRALXRLG FSPXQVXXIVX DVK (SEQ ID NO:24); DEEAERIVRE LXXRGVXXXX IXEILKRAGL SDEQVKKLIR RVX (SEQ ID NO:25); DEEELRRELE KXXRKGXXXX VXRIARRIGI DDRQVEKLLK DIX (SEQ ID NO:26); DEEVERIVRE LXXRGIXXXX IXEILKKNGF DEKEVREIVE KVX (SEQ ID NO:27); DERLERRVEE LXXNGVXXXX IXEWLRRAGL SPDQVKEVID RVX (SEQ ID NO:28); KEEAEKIVRE LXXRGVXXXX IXDILKKAGL SDEDVKRLIR RVX (SEQ ID NO:29); or DEEAKKLVRK LXXNGVXXXX LXRALKRLGF SPEQVKKIVR DVX (SEQ ID NO:30), wherein each X is independently any amino acid.

82. A binding protein comprising a sequence that has 90% or greater sequence identity toDEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVT (SEQ ID NO:31); DEEAKKLVRK LIRNGVCCTR LLWALITLGF SPEQVKKIVR DVK (SEQ ID NO:32), DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVG (SEQ ID NO:33); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR EVR (SEQ ID NO:34); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:35); DEEAKKLVRE LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:36); DEEAKKLVRK LIRNGVSDNG LWVELASLGF SPEQVKKIVR DVR (SEQ ID NO:37); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVNKIVR DVR (SEQ ID NO:38); YEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:39); DEEAKKLVRK LIRNGVSDNG LWVALASLSF SPEQVKKIVR DVR (SEQ ID NO:40); DEEAKKLVRK LIRNGVSDNG LWVALAPLGF SPEQVKKIVR DVR (SEQ ID NO:41); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVW DVR (SEQ ID NO:42); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR YVR (SEQ ID NO:43); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR(SEQ ID NO:44); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQIKKIVR DVR (SEQ ID NO:45);DEEAKKLVRK LIRNGVSDNG LWVAPASLGF SPEQVKKIVR DVR (SEQ ID NO:46); DEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DFR (SEQ ID NO:47); DEDAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:48); DEEAKKLVRK LIRNCVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:49); DEEAKKLVCK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:50); NEEAKKLVRK LIRNGVSDNG LWVALASLGF SPEQVKKIVR DVR (SEQ ID NO:51); DERLERRVEE LKRNGVTDHG ISLWLLGAGL SPDQVKEVID RVL (SEQ ID NO:52); DERLERRVEE LKRNGVTDHG IVLWLLGAGL SPDQVKEVID RVL (SEQ ID NO:53); , wherein each X is independently any amino acid.

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