G protein-coupled receptors 61 and 62, member of the class A family of seven-transmembrane G protein-coupled receptors
This subgroup includes the orphan receptors GPR61 and GPR62, which are both constitutively active and predominantly expressed in the brain. While GPR61 couples to G(s) subtype of G proteins, the signaling pathway and function of GPR 62 are unknown. GPR61-deficient mice displayed significant hyperphagia and heavier body weight compared to wild-type mice, suggesting that GPR61 is involved in the regulation of food intake and body weight. GPR61 transcript expression was found in the caudate, putamen, and thalamus of human brain, whereas GPR62 transcript expression was found in the basal forebrain, frontal cortex, caudate, putamen, thalamus, and hippocampus. Both receptors share the highest sequence homology with each other and comprise a conserved subgroup within the class A family of GPCRs, which includes receptors for hormones, neurotransmitters, sensory stimuli, 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, which then activate the heterotrimeric G proteins. Members of this subgroup contain [A/E]RY motif, a variant of the highly conserved Asp-Arg-Tyr (DRY) motif found in the third transmembrane helix (TM3) of the class A GPCRs and important for efficient G protein-coupled signal transduction.