G-protein coupled receptor 4 (GPR4) belongs to a protein family comprised of 3 related G protein-coupled receptors (GPCRs): GPR4, OGR1/GPR68 and TDAG8/GPR65. Like all GPCRs, GPR4 structure is composed of seven-transmembrane-spanning domains linked by an N-terminal extracellular domain and a C-terminal intracellular domain
