Lectins facilitate calcium-induced fusion of phospholipid vesicles containing glycosphingolipids

Ca2+-induced fusion of phospholipid vesicles containing globoside (GL-4) or disialoganglioside (GDla) is several-fold slower than the fusion of the pure phospholipid vesicles. Lectins specific for these glycosphingolipids, soybean agglutinin and wheat germ agglutinin, respectively, enhance the rate of fusion when added to the vesicle suspension before the introduction of Ca2+. The enhancement depends on the lectin concentration and the time of preincubation with the lectin. We propose that lectins facilitate membrane fusion by inducing intermembrane contact, which is the first step in the overall process of membrane fusion, or by laterally phase separating the inhibitory glycolipids.