Activation of Coagulation Factor V by a Platelet Protease

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Abstract

Factor V must be converted to Factor Va in order to bind to a high affinity platelet surface site and participate in prothrombin activation. Osterud et al. (10) presented data that suggested that human platelets contain an activated form of Factor V and a Factor V activator. We find that the Factor V released when platelets are disrupted by freezing and thawing or sonication is activated 3- to 10-fold by thrombin as determined by coagulation assay and is therefore stored as the relatively inactive procofactor rather than in the active form Factor Va.

Authors

William H. Kane, Jozef S. Mruk, Philip W. Majerus