Selected Abstracts From the 14th Annual Meeting of the Japanese Societies of Hypertension

Abstract

Using two oligonucleotide probes which were synthesized based on the amino acid sequences of tryptic fragments obtained from purified bovine lung endothelin(ET) receptor, we isolated a cDNA encoding non-isopeptide-selective type of ET receptor (ET_B) from a human liver cDNA library. The cDNA encoded a protein of 426 amino acid residues with putative seven transmembrane segments, exhibiting a significant similarity with the G-protein-coupled receptor superfamily. The deduced amino acid sequence of human ET_B receptor was 88% and 64% identical to those of rat lung ET_B receptor and human ET-1-specific(ET_A) receptor, respectivaly. COS cells transfected with the cloned cDNA expressed the binding sites with high affinity for every ET or sarafotoxin(SRT) isopeptide. Modification of disulfide bridges, a N-terminal amino acid or C-terminal hydrophobic residues of the isopeptides markedly reduced their binding affinity for the expressed ET_B receptor (Fig.), suggesting that ET_B receptor recognizes the common structures for ET/SRT. The ET_B mRNAs were significantly expressed in porcine aortic intima but not in the media, which supports the previous observation by us [FEBS Lett. (1991) 282 103–106].