High-throughput Discovery of Antibodies against Understudied Membrane Proteins using mRNA

ABSTRACT Of the 20,000 genes in the human genome, approximately 4,000 are considered “druggable”. However, less than 10% of these druggable proteins are actually targeted by FDA-approved drugs. In 2014, the Illuminating the Druggable Genome (IDG) project was launched by the NIH to address the large number of druggable targets with high therapeutic value that are understudied. The IDG has selected 178 G protein-coupled receptors (GPCRs) and ion channels as a focus of their program, as these families make up the largest families of the druggable genome and have high potential to impact human health. Due to their difficult biology, many of them are completely unexplored. To enable this research, the IDG has called for the development of reagents such as monoclonal antibodies (MAbs) against these 178 GPCRs and ion channels, most of which currently have no commercially available high quality MAbs. MAbs that target membrane proteins such as GPCRs and ion channels can be exceptionally useful in research, diagnostic, and therapeutic applications. However, for most membrane proteins, there are no MAbs available that recognize the native protein on the cell surface. Efforts to identify MAbs against these challenging targets are limited by the difficulty of expressing and purifying membrane proteins in exogenous systems and by conventional MAb isolation strategies that immunize mice with purified protein. A novel approach to identify membrane protein MAbs in a high-throughput manner is needed to derive MAbs against these difficult targets.