title: Activated protein C inhibits platelet prothrombin-converting activity.
abstract: Bovine platelets that have been activated by thrombin facilitate the conversion of prothrombin to thrombin in the presence of calcium ions and factor Xa. Activated protein C, a vitamin-K-dependent plasma protein, inhibits this platelet prothrombin-converting activity. The inhibition is time dependent and is not reversed by increasing concentrations of factor Xa. However, factor Xa is able to protect the platelet prothrombin-converting activity from inactivation by activated protein C. The activated protein C causes a parallel loss of factor Xa receptor sites and platelet prothrombin-converting activity. Activated protein C may contribute to the regulation of clotting through inactivation of the platelet prothrombin-converting activity.
mesh_terms: D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D001777:Blood Coagulation; D001792:Blood Platelets; D001798:Blood Proteins; D002417:Cattle; D005165:Factor V / Q000037:antagonists & inhibitors; D005170:Factor X / Q000494:pharmacology; D007531:Isoflurophate / Q000494:pharmacology; D011516:Prothrombin / Q000378:metabolism*; D013917:Thrombin / Q000378:metabolism; D013997:Time Factors
chemical_list: D001798:Blood Proteins; D007531:Isoflurophate; D005165:Factor V; D011516:Prothrombin; D005170:Factor X; D013917:Thrombin