Other Proteins of the Hemostatic System

Proteins that do not fit into the previous functional categories are fibrinogen, factor XIII (the plasma protransglutaminase), and von Willebrand factor. 

Von Willebrand Factor Von Willebrand factor (vWF) is a multisubunit protein that serves both to anchor the platelets to the subendothelium and as a carrier protein for factor VIII in the plasma. The circulating vWF is the largest protein of the hemostatic system. It is made of protomeric units which themselves are dimers of the 250,000-Da vWF polypeptide chain. The vWF gene product is a single polypeptide chain that associates to form the dimeric protomer. Disulfide bonds link the two vWF monomer chains in the protomer. The 500,000-Da dimeric protomers further associate to form the more than 20,000,000-Da vWF molecules present in the circulation. Recognition sites are present on the von Willebrand factor 

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