FIG 2.

Function of the von Willebrand Factor (vWF) in blood clotting. (Top) In the absence of vascular damage, where there is low shear force, the vWF protein present in endothelial cells adopts a globular conformation. (Bottom) During vascular damage, vWF is released from endothelial cells (53), and increased shear forces due to blood flow result in the protein adopting a stretched conformation (48, 54, 55) that binds collagen, aggregates to form a web-like structure at the site of injury, and binds to GpIbα on platelets.