Variant ActRIIB Polypeptides Modulating Ligand Binding
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Solution Overview
Problem
There is a need for potent regulators of TGF-beta signaling to achieve significant physiological changes, such as altering red blood cell levels, bone, and cartilage development.
Innovation Solution
Variant ActRIIB polypeptides with altered binding affinity for ActRIIB-binding ligands are developed, including homomultimer and heteromultimer proteins, to selectively increase or decrease ligand binding activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variant ActRIIB polypeptides are designed to increase ligand-binding affinity, then the ability to regulate TGF-beta signaling is improved, but the complexity of protein engineering increases
Solution Approach 1:
The patent applies parameter changes by systematically modifying amino acid sequences at specific positions (K55, F82, L79, A24, K74, R64, P129, P130, E37, R40, D54, R56, W78, D80) to alter ligand-binding affinity. Each substitution represents a controlled parameter change that increases binding strength while maintaining the overall protein structure and function.
Solution Approach 2:
The invention applies local quality by making targeted amino acid substitutions at specific positions within the ActRIIB polypeptide sequence rather than modifying the entire protein. This allows precise control over binding affinity at the molecular level while preserving other functional regions of the protein.
2Reliability
If amino acid substitutions are made to alter binding affinity, then ligand-binding activity is improved, but the difficulty of manufacturing increases
Solution Approach 1:
The patent defines specific amino acid substitutions at predetermined positions that can be incorporated through standard recombinant DNA technology. The明确的 substitution positions (K55, F82, L79, etc.) simplify the manufacturing process by providing clear design specifications for protein production.
Solution Approach 2:
The invention segments the ActRIIB polypeptide into specific mutable regions (the listed amino acid positions) that can be independently modified. This segmentation allows for modular protein engineering where only specific residues need to be changed, simplifying the manufacturing workflow compared to de novo protein design.
3Reliability
If variant polypeptides are developed with altered binding affinity, then therapeutic effectiveness is improved, but the time required for development increases
Solution Approach 1:
The patent performs preliminary action by pre-identifying and characterizing specific amino acid positions (K55, F82, L79, A24, K74, R64, P129, P130, E37, R40, D54, R56, W78, D80) that influence ligand-binding affinity. This advance work creates a library of known effective substitutions that can be rapidly deployed in therapeutic development without requiring extensive new screening for each application.
Solution Approach 2:
The invention establishes a systematic framework for parameter changes at specific amino acid positions that has been pre-validated to affect binding affinity. This framework allows for rapid optimization of therapeutic variants by selecting from known effective substitutions rather than requiring de novo optimization for each therapeutic indication.
Data Source
AI summary
In certain aspects, the present invention provides compositions and methods for modulating (promoting or inhibiting) growth of red blood cells or a tissue, such as bone, cartilage, muscle, fat, and/or neuronal tissue. The present invention also provides methods of screening compounds that modulate activity of an ActRIIB protein and/or an ActRIIB ligand. The compositions and methods provided herein are useful in treating diseases associated with abnormal activity of an ActRIIB protein and/or an ActRIIB ligand.