relaxin-3 like peptide receptors, member of the class A family of seven-transmembrane G protein-coupled receptors
This G protein-coupled receptor subfamily is composed of the relaxin-3 like peptide receptors, RNL3R1 and RNL3R2, and similar proteins. The relaxin-3 like peptide family includes relaxin-1, -2, -3, as well as insulin-like (INSL) peptides 3 to 6. RNL3/relaxin-3 and INSL5 are the endogenous ligands for RNL3R1 and RNL3R2, respectively. RNL3R1, also called GPCR135 or RXFP3, is predominantly expressed in the brain and is implicated in stress, anxiety, feeding, and metabolism. Insulin-like peptide 5 (INSL5), the endogenous ligand for RNL3R2 (also called GPCR142 or RXFP4), plays a role in fat and glucose metabolism. INSL5 is highly expressed in human rectal and colon tissues. Both RNL3R1 and RNL3R2 signal through G(i) protein and inhibit adenylate cyclase, thereby inhibit cAMP accumulation. RNL3R1 is shown to activate Erk1/2 signaling pathway.