Cyclic Extracellular Loop Antigen for Multi-Transmembrane Protein Antibodies
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Solution Overview
Problem
Developing high-quality antibodies for multi-transmembrane proteins has been challenging due to their linear nature and the difficulty in maintaining their natural state, especially when used as antigens, which affects their efficacy in disease-related therapies such as cancer treatment.
Innovation Solution
A method involving the use of a single-loop peptide that mimics the extracellular loop of multi-transmembrane proteins, with the N-terminal and C-terminal fixed on a solid substrate or attached to a linker to form a cyclic structure, enhancing the antigen's affinity and binding ability to antibodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear transmembrane proteins are used as antigens, then the antigen preparation is simple, but the antibody binding affinity and specificity are insufficient
Solution Approach 1:
The patent applies curvature by transforming the linear antigen into a cyclic structure. The N-terminal and C-terminal of the extracellular loop are connected to form a closed ring, which mimics the natural curved conformation of the transmembrane protein's extracellular domain. This cyclic structure provides a three-dimensional surface that better accommodates antibody binding sites, thereby improving antibody binding affinity and specificity while maintaining relatively simple preparation procedures through recombinant expression systems.
2Productivity
If transmembrane proteins are expressed by recombination, then the production efficiency is improved, but the natural state and 3-dimensional structure are not maintained
Solution Approach 1:
The patent extracts the essential functional domain (extracellular loop) from the complete transmembrane protein structure. By isolating and expressing only the extracellular loop region, which contains the antibody binding sites, the method achieves high production efficiency through simple recombinant expression in bacterial systems. Simultaneously, the extracted loop is designed to form a cyclic structure that maintains the natural three-dimensional conformation, thus preserving the functional characteristics of the native protein without requiring complex membrane expression systems.
3Reliability
If animal cells are used for expression, then the protein quality is improved, but the expression probability is low and time and cost are increased
Solution Approach 1:
The patent creates a simplified copy of the natural transmembrane protein structure by expressing only the essential extracellular loop domain in bacterial systems. This copied structure, when cyclized, reproduces the key three-dimensional features and epitopes of the native protein sufficient for high-quality antibody generation. This approach avoids the complexity and time-consuming nature of animal cell expression systems while achieving comparable protein quality for immunization purposes, significantly reducing development time and cost.
Data Source
AI summary
A multi-transmembrane protein antigen includes a polypeptide corresponding to an extracellular loop of the multi-transmembrane protein, the N-terminal and C-terminal of the polypeptide being fixed on a solid substrate or the N-terminal and C-terminal being attached to both ends of a linker to form a cyclic structure, an antibody specifically binding to the antigen or an antigen-binding fragment thereof, and a method for screening an antibody specifically binding to the antigen. The present invention may be usefully employed for effective production of antibodies for multi-transmembrane proteins that play important roles in disease-related phenomena such as cell signaling.