RESUMEN
Cell surface molecules are important for development and function of multicellular organisms. Although several methods are available to identify ligand-receptor pairs, ELISA-based methods are particularly amenable to high-throughput screens. ELISA-based methods have high sensitivity and low false-positive rates for detecting protein-protein interaction (PPI) complexes. Here, we provide a detailed protocol for a 384-well ELISA-based PPI screening protocol for the identification of novel cell surface ligand-receptor interactions, together with considerations for validation of PPIs by biophysical methods. This PPI screen has been developed and tested for discovery of novel ligand-receptor pairs between human synaptic adhesion proteins, believed to play crucial roles in many steps of neurodevelopment, from neuronal maturation, to axon guidance, synapse connectivity, and pruning.