GPR37 （G-protein coupled receptor 37）, also known as ETBR-LP-1 （endothelin B receptor-like protein 1） or PAELR （Parkin-associated endothelin receptor-like receptor）, is a 587 amino acid （aa）, 7-transmembrane receptor for the neuroprotective and glioprotective factor prosaposin. It is predominantly expressed in neuronal cells, particularly in cerebellar Purkinje cells and the hippocampus. GPR37 is a substrate of the E3 ubiquitin ligase, parkin, which is upregulated during endoplasmic reticulum stress. In a juvenile form of Parkinson's disease, the accumulation of GPR37 contributes to stress-induced neuronal cell death. The extracellular domains （aa 27-265） of human and mouse GPR37 share 68% amino acid identity.