Orphan receptor with constitutive G(s) signaling activity that activate cyclic AMP. Promotes neurite outgrowth and blocks myelin inhibition in neurons (By similarity). Highly expressed and localized along the cytoplasmic membrane as well as in a perinuclear compartment. Mainly expressed in the brain. Selectively expressed in striatopallidal neurons in the striatum. Deficient mice show reduced striatal cyclic AMP production and selective alterations in instrumental conditioning. Belongs to the G-protein coupled receptor 1 family. Was originally (PubMed:14592418) thought to be a receptor for sphingosine 1-phosphate. It has been demonstrated that it is not the case in human.