Evidence for a factor promoting the conversion of VWF from low and intermediate to high molecular mass polymers on the platelet membrane

Abstract

On the membrane surface of resting platelets exists a factor capable of promoting the conversion of plasma von Willebrand factor from low and intermediate molecular mass to high molecular mass polymers. The process is accompanied by a parallel increase in the von Willebrand factor activity. This could be a regulatory system for the molecular mass distribution of von Willebrand factor during its lifetime in plasma. Glycoprotein Ib of the platelet membrane appears not to be involved in the process.