primate-specific mas-related G protein-coupled receptor subtype X-like, member of the class A family of seven-transmembrane G protein-coupled receptors
The Mas-related G-protein coupled receptor (Mrgpr) family constitutes a group of orphan receptors exclusively expressed in nociceptive primary sensory neurons and mast cells in the skin. Members of the Mrgpr family have been implicated in the modulation of nociception, pruritus (itching), and mast cell degranulation. The Mrgpr family in rodents and humans contains more than 50 members that can be grouped into 9 distinct subfamilies: MrgprA, B, C (MrgprX1), D, E, F, G, H (GPR90), and the primate-specific MrgprX subfamily. Some Mrgprs can be activated by endogenous ligands such as beta-alanine, adenine (a cell metabolite and potential transmitter), RF-amide related peptides, or salusin-beta (a bioactive peptide). However, the effects of these agonists are not clearly understood, and the physiological role of the individual receptor family members remains to be determined.