title: Antibodies to protease-activated receptor 3 inhibit activation of mouse platelets by thrombin.
abstract: Recent studies of mice deficient in the thrombin receptor, protease-activated receptor 1 (PAR1), provided definitive evidence for the existence of a second thrombin receptor in mouse platelets. We recently identified a new thrombin receptor designated protease-activated receptor 3 (PAR3). The mRNA encoding a mouse homologue of PAR3 was highly expressed in mouse splenic megakaryocytes, making it a good candidate for the missing mouse platelet thrombin receptor. We now report that PAR3 protein is expressed on the surface of mouse platelets and that PAR3 antibodies partially inhibit activation of mouse platelets by thrombin but not U46619, a thromboxane receptor agonist. These observations suggest that PAR3 contributes to mouse platelet activation by thrombin.
authors.affiliation: Cardiovascular Research Institute, Daiichi Research Center, University of California, San Francisco, San Francisco, CA 94143-0130, USA.
authors.forename: H
authors.initials: H
authors.lastname: Ishihara
authors.forename: D
authors.initials: D
authors.lastname: Zeng
authors.forename: A J
authors.initials: AJ
authors.lastname: Connolly
authors.forename: C
authors.initials: C
authors.lastname: Tam
authors.forename: S R
authors.initials: SR
authors.lastname: Coughlin
mesh_terms: D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid / Q000494:pharmacology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D019556:COS Cells; D029742:Caenorhabditis elegans Proteins; D004347:Drug Interactions; D015801:Helminth Proteins / Q000276:immunology* / Q000502:physiology*; D007074:Immunoglobulin G / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D015539:Platelet Activation / Q000187:drug effects*; D017346:Protein Serine-Threonine Kinases; D013917:Thrombin / Q000494:pharmacology*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
chemical_list: D000911:Antibodies, Monoclonal; D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D007074:Immunoglobulin G; D014662:Vasoconstrictor Agents; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; C097238:PAR-3 protein, C elegans; D017346:Protein Serine-Threonine Kinases; D013917:Thrombin