putative purinergic receptor GPR174, member of the class A family of seven-transmembrane G protein-coupled receptors
GPR174 has been recently identified as a lysophosphatidylserine receptor that enhances intracellular cAMP formation by coupling to a G(s) protein. GPR174 is a member of the rhodopsin-like, class A GPCRs, which is a widespread protein family that includes the light-sensitive rhodopsin as well as receptors for biogenic amines, lipids, nucleotides, odorants, peptide hormones, and a variety of other ligands. All GPCRs have a common structural architecture comprising of seven-transmembrane (TM) alpha-helices interconnected by three extracellular and three intracellular loops. A general feature of GPCR signaling is agonist-induced conformational changes in the receptors, leading to activation of the heterotrimeric G proteins, which consist of the guanine nucleotide-binding G-alpha subunit and the dimeric G-beta-gamma subunits. The activated G proteins then bind to and activate numerous downstream effector proteins, which generate second messengers that mediate a broad range of cellular and physiological processes.