Affibody Molecules Targeting GPCR Transmembrane Clefts
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Solution Overview
Problem
Developing effective therapeutic agents that can target G-protein coupled receptors (GPCRs) is challenging due to their structural constraints, particularly the ligand binding site within the transmembrane cleft of Family 1 GPCRs, making it difficult to generate monoclonal antibodies or small molecules that can modulate these receptors effectively.
Innovation Solution
The use of amino acid sequences, specifically Nanobodies, that can bind to GPCRs with high affinity and specificity through extended CDR loops, allowing for modulation of GPCR-mediated signaling and treatment of associated diseases by targeting various GPCR families, including Class A, B, and C receptors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional small molecules or monoclonal antibodies are used to target GPCRs, then the drug development process follows conventional approaches, but the ability to effectively access and modulate the ligand binding site within the transmembrane cleft is limited due to structural constraints
Solution Approach 1:
The patent uses an affibody molecule as an intermediary binding agent that can access the transmembrane cleft of GPCRs. The affibody comprises a specific amino acid sequence (SEQ ID NO: 2) that enables it to penetrate and bind to the ligand binding site within the transmembrane domain, serving as a mediator that overcomes the structural barriers that prevent traditional antibodies from accessing this region.
Solution Approach 2:
The patent changes the structural parameters of the binding agent by using a small, compact affibody molecule (approximately 6.5 kDa) instead of large monoclonal antibodies. This size reduction and structural simplification allows the molecule to access the confined transmembrane cleft space, fundamentally changing the physical parameters (size, shape, flexibility) needed to overcome GPCR structural constraints.
2Ease of manufacture
If monoclonal antibodies are generated to target GPCRs, then conventional immunotherapy approaches are applied, but the generation of effective antibodies is difficult due to the 7 membrane-spanning helix architecture and aggregation tendency of GPCRs
Solution Approach 1:
The patent employs a disposable, single-use affibody molecule with a simple, well-defined amino acid sequence that can be produced through straightforward recombinant expression. This approach replaces the complex, time-consuming process of generating and characterizing monoclonal antibodies with a simpler, more reliable system based on a predetermined molecular structure that naturally binds to GPCRs.
3Reliability
If extended CDR loops are used in Nanobodies to bind GPCRs, then high affinity and specificity are achieved, but the structural complexity of the amino acid sequence increases
Solution Approach 1:
The patent applies local quality by concentrating binding specificity in the extended CDR loops (particularly CDR3) of the affibody molecule, while keeping the framework regions simple and standardized. This allows the complex binding function to be localized to specific amino acid residues in the CDR regions, achieving high affinity and specificity without requiring the entire molecule to be structurally complex.
Data Source
AI summary
The present invention relates to amino acid sequences that are directed against G-protein coupled receptors (GPCRs), as well as to compounds or constructs, and in particular proteins and polypeptides, that comprise or essentially consist of one or more such amino acid sequences. The invention also relates to nucleic acids encoding such amino acid sequences and; to methods for preparing such amino acid sequences and polypeptides; to host cells expressing or capable of expressing such amino acid sequences or polypeptides; to compositions, and in particular to pharmaceutical compositions, that comprise such amino acid sequences, polypeptides, nucleic acids and/or host cells; and to uses of such amino acid sequences or polypeptides, nucleic acids, host cells and/or compositions, in particular for prophylactic, therapeutic or diagnostic purposes.