title: Receptors for relaxin family peptides.
abstract: Recent studies have identified four receptors that are the physiological targets for relaxin family peptides. All are class I (rhodopsin like) G-protein-coupled receptors with LGR7 (RXFP1) and LGR8 (RXFP2) being type C leucine-rich repeat-containing receptors, whereas GPCR135 (RXFP3) and GPCR142 (RXFP4) resemble receptors that respond to small peptides such as somatostatin and angiotensin II. The cognate ligands for the receptors have been identified: relaxin for RXFP1; INSL3 for RXFP2; relaxin 3 for RXFP3 and INSL5 for RXFP4. RXFP1 and RXFP2 receptors produce increases in intracellular cAMP levels upon stimulation, although the response is complex and contains a component sensitive to PI-3-kinase inhibitors. There is also evidence that RXFP1 can activate Erk1/2 and nitric oxide synthase, and relaxin has been reported to enter cells and activate glucocorticoid receptors. In contrast, RXFP3 and RXFP4 couple to Gi by a pertussis toxin-sensitive mechanism to cause inhibition of cAMP production. Now that the receptors for relaxin family peptides and their cognate ligands have been identified, we suggest a nomenclature for both the peptides and the receptors that we hope will be helpful to researchers in this rapidly advancing field.
authors.affiliation: Howard Florey Institute of Experimental Physiology and Medicine, University of Melbourne, Victoria 3010, Australia.
authors.forename: Ross A
authors.initials: RA
authors.lastname: Bathgate
authors.forename: Richard
authors.initials: R
authors.lastname: Ivell
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Sanborn
authors.forename: O David
authors.initials: OD
authors.lastname: Sherwood
authors.forename: Roger J
authors.initials: RJ
authors.lastname: Summers
mesh_terms: D000818:Animals; D015870:Gene Expression; D006801:Humans; D008024:Ligands; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012065:Relaxin / Q000145:classification* / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D008024:Ligands; D043562:Receptors, G-Protein-Coupled; D018000:Receptors, Peptide; C033395:relaxin receptors; D012065:Relaxin