Comparison of the active sites in the vWF-A1 and vWF-A2 domains. The upper panels compare the ristocetin-binding residues in the vWF-A1 domain with the Mg²⁺ binding site in the CR3 vWF-A domain. These residues are shown as dot representation of the van der Waal radii of the residues in question. For comparison with Fig 6, the type 2M and 2B mutation sites in the vWF-A1 domain are indicated using spheres at the α-carbon positions. The lower panels show the proposed heparin binding site on the α-helices A3 and A4 in the vWF-A1 domain, and the protease cleavage site at Y842-M843 on the vWF-A2 domain, also using α-carbon positions.