CLONING AND EXPRESSION OF A CDNA FOR THE HUMAN PROSTACYCLIN RECEPTOR

A functional cDNA for the human prostacyclin receptor was isolated from a cDNA library of CMK cells, a human megakaryocytic leukaemia cell line. The cDNA encodes a protein consisting of 386 amino acid residues with seven putative transmembrane domains and a deduced molecular weight of 40,956. [H-3]Iloprost specifically bound to the membrane of CHO cells stably expressing the cDNA with a K-d of 3.3 nM. This binding was displaced by unlabelled prostanoids in the order of iloprost = cicaprost >> carbacyclin > prostaglandin E(1) (PGE(1)) > STA(2) PGE(2), PGD(2) and PGF(2 alpha) did not inhibit it. Iloprost in a concentration-dependent manner increased the cAMP level and generated inositol trisphosphate in these cells, indicating that this human receptor can couple to multiple signal transduction pathways.