Mas-related G protein-coupled receptor member X1 (MRGX) is a sensory neuron-specific G protein-coupled receptor that is involved in the development and function of nociceptive neurons and may also regulate the sensation or modulation of pain. MRGPRX2, is a 330 amino acid multi-pass membrane protein that functions as an orphan receptor and, like MRGX, is thought to be involved in the function of nociceptive neurons. Expressed in the central nervous system with highest expression in dorsal root ganglia, MRGX2 may also be involved in cortistatin function, possibly playing a role in sleep regulation and cortical function.