Mast cell-specific receptor for basic secretagogues, i.e. cationic amphiphilic drugs, as well as endo- or exogenous peptides, consisting of a basic head group and a hydrophobic core (PubMed:25517090). Recognizes and binds small molecules containing a cyclized tetrahydroisoquinoline (THIQ), such as non-steroidal neuromuscular blocking drugs (NMBDs), including tubocurarine and atracurium. In response to these compounds, mediates pseudo-allergic reactions characterized by histamine release, inflammation and airway contraction (By similarity). Acts as a receptor for a number of other ligands, including peptides and alkaloids, such as cortistatin-14, proadrenomedullin N-terminal peptides PAMP-12 and, at lower extent, PAMP-20, antibacterial protein LL-37, PMX-53 peptide, beta-defensins, and complanadine A. Mainly expressed in mast cells. Has a limited expression profile, both peripheral and within the central nervous system, with highest levels in dorsal root ganglion (PubMed:12915402). Detected in blood vessels, scattered lymphocytes, and gastrointestinal ganglia (at protein level) (PubMed:16161007). Belongs to the G-protein coupled receptor 1 family. Mas subfamily.