Vol. 189, No. 2, 1992 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS December 15. 1992 Pages 617-624 Molecular Cloning and Characterization of the Platelet-Activating Factor Receptor Gene Expressed in the Human Heart Tom Sugimoto 1, Hidetsugu Tsuchimochi 1, Christopher G.A. McGregor 3, Hiroyuki Mutoh4, Takao Shimizu 4, and Yoshihisa Kurachi 1.2) 1 Division of Cardiovascular Diseases, Department of Internal Medicine, 2 Department of Pharmacology, and 3 Division of Thoracic and Cardiovascular Surgery, Department of Surgery, Mayo Clinic, Mayo Foundation, Rochester MN 55905 4 Department of Biochemistry, Faculty of Medicine, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan Received October 24, 1992 PAF decreases cardiac contractility and blood pressure. To characterize the cardiac PAF receptor, we screened a human ventricular cDNA library in a low stringency condition, using a PCR product derived from guinea pig lung PAF receptor as a probe. Four clones were obtained and named HVl-4. In Xenopus oocytes injected with cRNA derived from HV3 or 4 but not from HVl or 2, PAF elicited a Ca2+-activated Cl- current. HV3 and HV4 were duplicate clones, encoding a 342 amino-acid polypeptide which was identical to that of the human leukocyte PAF receptor. However, a portion of the 5’ untranslated region of HV3 (or 4) was different from that of the leukocyte receptor cDNA. Northern blotting of human ventricles and atria using the HV3 insert showed a single band of -4 kb. These results suggest a tissue-specific translational mechanism responsible for regulation of the expression of the PAF receptor mRNA in these tissues. 0 1992 Academic Press, Inc. PAF, a phospholipid released from stimulated basophils, platelets, macrophages, and polymorphonuclear neutrophils, produces, even at nanomolar concentrations, dramatic cardiovascular effects such as peripheral vasodilation with hypotension, decrease in cardiac output, increase in vascular permeability, coronary vasoconstriction and arrhythmias ( 1,2). Besides being *To whom correspondence should be addressed. Abbreviations: PAF, platelet-activating factor; PCR, polymerase chain reaction; cRNA, complementary RNA. 0006-291X/92 $4.00 617 Copyright 0 I992 by Academic Press, Inc. All rights of reproduction in any form reserved.