MRGX1 is an opiod receptor that has been reported exclusively in dorsal root ganglion. MRGX1 is probably involved in the function of nociceptive neurons and may regulate nociceptor function and/or development, including the sensation or modulation of pain. It is potently activated by enkephalins including BAM22 (bovine adrenal medulla peptide 22) and BAM (8-22). BAM22 is the most potent compound and evoked a large and dose-dependent release of intracellular calcium in stably transfected cells.