Function-based high-throughput screening for antibody antagonists and agonists against G protein-coupled receptors

Ren et al. develop a function-based high-throughput screening method for identifying antibody antagonists and agonists against GPCRs by combining GPI-anchored antibody cell surface display and beta-arrestin recruitment reporter assay. They identify a panel of antibody antagonists and an agonist to the human apelin receptor, which is not obtainable from phage display technology. Hybridoma and phage display are two powerful technologies for isolating target-specific monoclonal antibodies based on the binding. However, for complex membrane proteins, such as G protein-coupled receptors (GPCRs), binding-based screening rarely results in functional antibodies. Here we describe a function-based high-throughput screening method for quickly identifying antibody antagonists and agonists against GPCRs by combining glycosylphosphatidylinositol-anchored antibody cell display with beta-arrestin recruitment-based cell sorting and screening. This method links antibody genotype with phenotype and is applicable to all GPCR targets. We validated this method by identifying a panel of antibody antagonists and an antibody agonist to the human apelin receptor from an immune antibody repertoire. In contrast, we obtained only neutral binders and antibody antagonists from the same repertoire by phage display, suggesting that the new approach described here is more efficient than traditional methods in isolating functional antibodies. This new method may create a new paradigm in antibody drug discovery.