Reconstitution of liposomes bearing platelet receptors for human von Willebrand factor

Abstract

The authors describe a method of reconstitution of lipidic vesicles bearing glycoprotein I isolated from human platelet membranes. Briefly, the glycoprotein is solubilized from plasma membrane with Na-deoxycholate and purified by wheat-germ agglutinin affinity chromatography. After replacement of deoxycholate by TRITON X 100, the glycoprotein is mixed with pure egg-phosphatidylcholine solubilized by the same detergent. Removal of Triton yields large, unilamellar lipidic vesicles as assessed by electron microscopy. Theses vesicles are reversibly agglutinable by wheat-germ agglutinin. When incubated with purified von Willebrand factor, a strong, ristocetin-independent, agglutination occurs, whereas ristocetin alone has no effect. This membrane model provides a new tool for studing the structure and function of the platelet membrane.