Orphan receptor with constitutive G(s) signaling activity that activate cyclic AMP. Has a potential role in modulating a number of brain functions, including behavioral responses to stress, amyloid-beta peptide generation in neurons (By similarity) and neurite outgrowth (By similarity). Maintains also meiotic arrest in oocytes. Expressed in both the forebrain and hindbrain, with the highest level in habenula. Lower level expression in the testis. Highly expressed in regions. Mice are fertile but display progressive reduction in litter size despite a stable age-independent alteration of the meiotic pause, characterized by premature resumption of meiosis in about one-third of antral follicles in mutant females regardless of age. Aging mutant mice had severe reduction of fertility, manifested by an increasing number of nondeveloping early embryos upon spontaneous ovulation and massive amounts of fragmented oocytes after superovulation. Belongs to the G-protein coupled receptor 1 family.