● ● ● HEMOSTASIS Comment on Lisman et al, page 3753 When collagen meets VWF

In this issue ofBlood, Lisman and colleagues report on the identification of the VWF-binding site within collagen III: of 57 triple-helical peptides spanning the whole triple-helical domain, one single 27-residue collagen III sequence, with an essential 9-residue stretch, sustained binding of the VWF A3 domain. Von Willebrand factor (VWF) forms abridge between collagens within the con-nective tissue exposed upon damage of the blood vessel and the platelet membrane glyco-protein Ib (GPIb), and therefore plays a piv-otal role in the formation of an arterial platelet-rich thrombus. Several types of fibrillar collagen bind VWF, the major collagen-bind-ing site of which is located within the A3 do-main,1 with a second site in the A1 domain.2 Collagen types I and III, in particular, provide strong binding sites for VWF. Although th