This domain family is found in bacteria, and is approximately 100 amino acids in length. The family is found in association with Pfam:PF00092. There are two conserved sequence motifs: STF and DVD. There are two completely conserved residues (E and N) that may be functionally important. In hemostasis, platelet adhesion to the damaged vessel wall is mediated by several proteins, including von Willebrand factor. In solution vWF becomes immobilized via its A3 domain on the fibrillar collagen of the vessel wall and acts as an intermediary between collagen and the platelet receptor glycoprotein Ibalpha (GPIbalpha), which is the only platelet receptor that does not require prior activation for bond formation.

1: Function of von Willebrand factor in haemostasis and thrombosis. Reininger AJ; Haemophilia. 2008;14:11-26. PMID:18786007