A new family of orphan G protein-coupled receptors predominantly expressed in the brain.

The cloning of a cDNA encoding a G protein-coupled receptor homologous to the endothelin type B receptor, but unable to bind endothelin, was recently reported and termed ET(B)R-LP. We report here the isolation of a human cDNA encoding a receptor that is highly related to ET(B)R-LP and which was therefore termed ET(B)R-LP-2. Comparison of the two amino acid sequences revealed 68% overall homology and 48% identity. As is the case for ET(B)R-LP, the new receptor is strongly expressed in the human central nervous system (e.g. in cerebellar Bergmann glia, cerebral cortex, internal capsule fibers). Membranes of HEK-293 cells stably expressing ET(B)R-LP-2 did not bind endothelin-1, endothelin-2, endothelin-3, bombesin, cholecystokinin-8 or gastrin-releasing peptide.