Members of the mas-related receptor family (also known as oncogene-like MAS and mas-related G-protein coupled receptor MRG) have been implicated in the development, regulation and function of nociceptive neurons, specifically in the modulation of pain. Most members are orphaned, with no endogeneous ligand identified. Of the human mas-related GPCRs, four (MRGPRD, MRGPRE, MRGPRF and MRGPRG) are also found in rodents, whereas MRGPRX1, MRGPRX2, MRGPRX3 and MRGPRX4 are found exclusively in primates. Certain rodent MRGs have been reported to respond to adenine []and to RF-amide peptides, including neuropeptide FF [, ], but the relevance of these findings to man is unclear. MRGs are expressed predominantly in small diameter sensory neurons of the dorsal root ganglia, where there is emerging evidence that they may be mediators of histamine-independent itch [, ].This entry represents mas-related G protein-coupled receptor D (MRGPRD), it is thought to be involved with nociceptor function and development, and is directly involved in the modulation of pain. It has been demonstrated that beta-alanine can act as an agonist at MRGPRD [].
