Von Willebrand Factor is a blood multimeric glycoprotein which is synthetized by endothelials cells of the blood vessels and megakaryocytes of the bone marrow. It is found as big multimer in platelet and endothelials cells. In the plasma it is cleaved by metalloprotease into smaller multimers. Each multimer is composed of numerous dimers made of two identical subunits which contains several domains : D’-D3-A1-A2-A3-D4-B1-B2-B3-C1-C2-C3CK. It is the biggest protein in the blood.
When a blood vessel is damaged , some mechanisms come into play in order to stop the bleeding. It is called hemostasis process and the Von Willebrand factor is involved into it.
Synthesis
Function
Von Willebrand factor has two mainly functions in diferent phenomenon :
- Coagulation : act as a carrier for the plasma procoagulant co-enzyme, factor VIII. Factor VIII bound to VWF is protected from
inactivation by proteases. Factor VIII is released from VWF by the action of thrombin.
- Platelet plug formation : promote platelet adhesion to thrombogenic surfaces and their aggregation
This factor is also bound to :
- collagen when the blood vessel is damaged by its A1 and A3 domains
- Platelet integrins αIIb/β3 by the C1 domain (which contains the RGD pattern)
Disease
Relevance
Structural highlights
Image:Structure I VWF.jpg
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