Interaction between Glycophorin and Ganglioside GM₁ on Liposomal Membranes. Effect of the Interaction on the Susceptibility of Membranes to HVJ

Abstract

Liposomes could bind and fuse efficiently to human erythrocytes in the presence of HVJ when they contained glycophorin isolated from human erythrocytes (Umeda, M., et al. (1983) J. Biochem. 94, 1955). In the present work we demonstrated that HVJ-induced fusion between liposomes containing glycophorin and erythrocytes was suppressed when GM₁ coexisted with glycophorin in the same liposomal membranes. Asialo-GM₁ and other gangliosides such as GM₃ and sialosylparagloboside did not affect the fusion between the liposomes and erythrocytes. An intermolecular interaction between glycophorin and GM₁ was suggested by the ESR spectrum obtained from liposomes containing glycophorin and a ganglioside GM₁ analog carrying a nitroxyl spin label in the fatty acyl chains (5 SL-gangliosidoide). The overall splitting value (2 A _//) observed in the ESR spectrum of liposomes containing 5 SL-gangliosidoide increased with increase of the amount of glycophorin, whereas 2 A _// of spin-labeled phosphatidylcholine was not changed. The increase of 2 A _// of 5 SL-gangliosidoide suggests that the mobility of the fatty acyl chain of the gangliosidoide was restricted by the interaction with glycophorin. It can be concluded that GM₁ located near glycophorin, a receptor of the virus, interferes with the activity of viral F protein, inhibiting the fusion of liposome to erythrocyte.