Molecular Cloning and Functional Analysis of a Novel P Nucleotide Receptor

• Published in: The Journal of biological chemistry 1995-11, Vol.270 (44), p.26152
• Main Authors: Kyungho Chang, Kazuo Hanaoka, Mamoru Kumada, Yoh Takuwa
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.44.26152

The cDNA encoding a novel P receptor was isolated from rat aortic smooth muscle cell library and functionally characterized. The cloned P receptor exhibits structural features characteristic of the G protein-coupled receptor family and shows 44 and 38% amino acid identity with previously cloned rat P and chicken P receptors, respectively. The cloned P receptor is functionally coupled to phospholipase C but not to adenylate cyclase in C6 rat glioma cells transfected with the cloned P expression vector. The rank order of agonist potency as judged by intracellular Ca mobilization responses is UTP > ADP = 2-methylthioATP > ADPβS > ATP = ATP S, which is not compatible with any of the previously characterized P receptor subtypes. The nonselective P antagonists, suramin and reactive blue-2, inhibit nucleotide-induced phospholipase C activation in cells expressing the cloned P receptor. The cloned P receptor mRNA is abundantly expressed in various rat tissues including lung, stomach, intestine, spleen, mesentery, heart, and, most prominently, aorta. The results indicate that the novel metabotropic P receptor has pharmacological characteristics distinct from any of P receptor subtypes thus far identified and suggest the existence of a novel regulatory system by extracellular nucleotides of potential significance.