Molecular cloning and pharmacological characterization of a somatostatin receptor subtype in the gymnotiform fish Apteronotus albifrons

Abstract

The actions of the various forms of somatostatin (SRIF), including those of the tetradecapeptide SRIF14, are mediated by specific receptors. In mammals, five subtypes of SRIF receptors, termed sst1-5, have been cloned. Using a combination of reverse transcriptase-polymerase chain reaction and genomic library screening in the gymnotiform fish Apteronotus albifrons, a gene encoding the first-known nonmammalian SRIF receptor has been isolated. The deduced amino acid sequence displays 59% identity with the human sst3 receptor protein; hence, the gene is termed 'Apteronotus sst3.' The predicted protein consists of 494 amino acid residues exhibiting a putative seven-transmembrane domain topology t..