VWF Polyclonal antibody

Von Willebrand factor (VWF) is a large multimeric glycoprotein found in blood plasma involved in hemostasis following vascular injury. 

What is the molecular weight of VWF?

Due to the multimeric nature of VWF, it can range in size from 500 to 20,000 kDa due to the differences in the number of subunits comprising the protein. Each subunit is approximately 250 kDa (PMID: 9759493). 

What is the tissue specificity of VWF?

The biosynthesis of VWF in vivo is limited to endothelial cells (PMID: 4209883) and megakaryocytes (PMID: 2413071). VWF synthesized in endothelial cells is either released directly into the plasma via a secretory pathway, or tubulized and stored in organelles unique to this cell type called Weibel-Palade bodies (PMID: 16459301). Whereas VWF synthesized in megakaryocytes is stored in the alpha granules of platelets (PMID: 2046403). 

What is the function of VWF?

The primary function of VWF is as an adhesive plasma glycoprotein, particularly factor VIII; an essential blood-clotting protein (PMID: 6982084). VWF is also important in platelet adhesion to wound sites by binding specifically to type I and type III collagen (PMID: 11098050), with larger VWF multimers being most effective (PMID: 24448155). 

What is the importance of post-translational modifications (PTMs) on VWF function?

During the synthesis of VWF, it must undergo extensive PTMs. The VWF monomers are subsequently N-glycosylated with the addition of a 12 N-linked high-mannose-containing oligosaccharide after the cleavage of the signal peptide in the endoplasmic reticulum. Dimerization of the pro-VWF follows glycosylation via carboxyl-termini disulphide bond formation. In the Golgi apparatus, the oligosaccharide chains are further modified into complex carbohydrates and multimerization of pro-VWF dimers occurs after another round of disulphide bond formation at the amino-termini end of the subunits (PMID: 6334089).