N-arachidonyl glycine receptor, GPR18, member of the class A family of seven-transmembrane G protein-coupled receptors
N-arachidonyl glycine (NAGly), an endogenous metabolite of the endocannabinoid anandamide, has been identified as an endogenous ligand of the G(i/o) protein-coupled receptor 18 (GPR18). NAGly is involved in directing microglial migration in the CNS through activation of GPR18. NAGly-GPR18 signaling is thought to play an important role in microglial-neuronal communication. Recent studies also show that GPR18 functions as the abnormal cannabidiol (Abn-CBD) receptor. Abn-CBD is a synthetic isomer of cannabidiol and is inactive at cannabinoid receptors (CB1 or CB2), but acts as a selective agonist at GPR18. The NAGly receptor is a member of the class A G protein-coupled receptor superfamily, which all 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, which then activate the heterotrimeric G proteins. G-proteins regulate a variety of cellular functions including metabolic enzymes, ion channels, and transporters, among many others.
Comment:based on the structures of some class A family members with bound ligands (peptides or chemicals), agonists, or antagonists
Comment:Small-molecule chemical ligands tend to bind deeper within the receptor core, compared to a peptide ligand neurotensin, which binds towards the extracellular surface of its receptor.
Jiyao W et al.(2023). "The conserved domain database in 2023.",