An evolutionarily conserved G-protein coupled receptor family, SREB, expressed in the central nervous system

We report here a novel family of G-protein coupled receptor (GPCR) which is extraordinarily conserved among vertebrate species. This family, designate d SREB (Super Conserved Receptor Expressed in Brain), consists of at least three members, termed SREB1, SREB2, and SREB3. SREB members share 52-63% am ino acid identity with each other and show relatively high similarity to pr eviously known amine amine GPCRs (approximately 25% identity). Amino acid s equence identity between human and rat orthologues is 97% for SREB1 and 99% for SREB3, while the SREB2 sequence is surprisingly completely identical b etween the species. Furthermore, amino acid sequence of zebrafish SREB2 and SREB3 are 94 and 78% identical to mammal orthologues. Northern blot analys is revealed that SREB members are predominantly expressed in the brain regi ons and genital organs. Radiation hybrid analysis localized SREB1, SREB2, a nd SREB3 genes to different human chromosomes, namely 3p21-p14, 7q31 and Xp 11, respectively. The high sequence conservation and abundant expression in the central nervous system suggest the existence of undiscovered fundament al neuronal systems consisting of SREB family members and their endogenous ligand(s). (C) 2000 Academic Press.