Orphan receptor. Displays a significant level of constitutive activity. Its effect is mediated by G(s)-alpha protein that stimulate adenylate cyclase, resulting in an elevation of intracellular cAMP. Highly expressed in the CNS, the highest expression is seen in the amygdala, hippocampus and thalamus. Weak expression is detected in testis. Down-regulated in glioblastoma. Belongs to the G-protein coupled receptor 1 family.