Enables transmembrane signaling receptor activity. Involved in cell surface receptor signaling pathway and response to chloroquine. Acts upstream of or within chemosensory behavior. Located in axon and neuronal cell body membrane. Orthologous to several human genes including MRGPRX1 (MAS related GPR family member X1); MRGPRX2 (MAS related GPR family member X2); and MRGPRX3 (MAS related GPR family member X3).