Multiple Lectins in Two Species of Cellular Slime Molds

Abstract

Evidence has been presented in the preceding communication (Barondes and Rosen, elsewhere this volume) that specific cell cohesion in the cellular slime molds is accomplished by the interaction of carbohydrate-binding lectins with complementary cell surface oligosaccharide-containing receptors. In the species Dictyostelium discoideum and Polysphondylium pallidum both the lectins (1, 3, 5) and their surface receptors (2) are developmentally regulated. That is, both are absent in feeding, vegetative amoebae and appear as the starved cells differentiate and become cohesive. The proteins responsible for the lectin (red cell agglutination) activity of crude extracts of five species of cellular slime mold have been purified and partially characterized. Several of these lectins exhibit heterogeneity. In particular, cohesive D), discoideum cells contain two structurally and functionally distinct lectins and cohesive P. pallidum cells contain three.