ASP514 within the A1 domain of bovine von Willebrand factor is required for interaction with platelet glycoprotein Ib.

ABSTRACT

A mutant PAD-1 (D514-->Q) of the recombinant fragment PAD-1 comprising Leu469-Ser723 of the A1 domain of bovine von Willebrand factor (vWF) neither inhibited the binding of [125I]vWF to platelets nor the agglutination of human platelets induced by bovine vWF. PAD-1, on the other hand, inhibited human platelet agglutination induced by bovine vWF and [125I]vWF binding to human platelets. Collagen binding properties of the mutant, however, were indistinguishable from those of PAD-1. These results suggested that Asp514 within the A1 domain of vWF is required for interaction of bovine vWF with GPIb receptor on human platelets.