GPCR Targeted Library
G protein-coupled receptors (GPCRs), also known as seven-(pass)-transmembrane domain receptors is a large group of evolutionary related proteins that are cell surface receptor that detect molecules outside the cell and activate cellular responses. Coupling with G proteins, they are called seven-transmembrane receptors because they pass through the cell membrane seven times. The ligands that bind and activate these receptors include light-sensitive compounds, odors, pheromones, hormones, and neurotransmitters, and vary in size from small molecules to peptides to large proteins. There are two principal signal transduction pathways involving the G protein-coupled receptors: the cAMP signal pathway and the phosphatidylinositol signal pathway.
G protein-coupled receptors are involved in many diseases. GPCRs have been of long-standing interest as pharmacological targets, as they regulate numerous diverse physiological processes and have druggable sites that are accessible at the cell surface. Drugs that target GPCRs also account for ~27% of the global market share of therapeutic drugs. New avenues for GPCR drug discovery have emerged owing to recent advances in receptor pharmacology, breakthroughs in structural biology and innovations in biotechnology. The major disease indications for GPCR modulators show a shift towards diabetes, obesity and Alzheimer disease, although several central nervous system disorders are highly represented. 
 A. S. Hauser, M. M. Attwood, M. Rask-Andersen, H. B. Schiöth, and D. E. Gloriam, “Trends in GPCR drug discovery: New agents, targets and indications,” Nat. Rev. Drug Discov., vol. 16, no. 12, pp. 829–842, 2017, doi: 10.1038/nrd.2017.178.