Complex carbohydrate-lectin interaction at the interface: a model for cellular adhesion. II. Reactivity of both the oligosaccharide chain and sugar-binding domain of a glycoprotein lectin.
We describe studies of a new model cell adhesion system involving liposomes bearing lectins and the glycosphingolipid, asialomonosialoganglioside (asialoGM1). The model provides a simple analysis of experimental data to elucidate the mechanism of heterophilic cell-cell adhesion mediated by multiple protein-carbohydrate interactions. Phospholipid vesicles bearing the fatty acid conjugate of a glycoprotein lectin from Ricinus communis (RCAI vesicle) are shown to react with vesicles bearing the fatty acid conjugate of Concanavalin A (Con A) and asialoGM1 (Con A vesicle). The kinetics of aggregation and monosaccharide-induced disaggregation of the two types of vesicles were followed by monitoring the time-dependent change in turbidity. Depending on the surface density of the asialoGM1, 40-60% of the resulting precipitin complex was dissociable only in the presence of both RCAI-specific galactose and Con A-specific alpha-methyl-D-mannoside. Results indicate simultaneous participation of both the saccharide-binding domain and carbohydrate sequence of RCAI, a model cell adhesion molecule, to stabilize the encounter complex by two types of interactions. These findings support the possibility of stable cell-cell adhesion in vivo occurring via interactions between cell adhesion molecules on apposing cell-surface membranes.
Chakrabarti
A
A
Department of Biochemistry, Indian Institute of Science, Bangalore.
Podder
S K
SK
D050260:Carbohydrate Metabolism; D002448:Cell Adhesion / Q000502:physiology*; D003208:Concanavalin A / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine / Q000378:metabolism; D005677:G(M1) Ganglioside / Q000378:metabolism; D037102:Lectins / Q000378:metabolism*; D008081:Liposomes; D008954:Models, Biological; D037121:Plant Lectins
D037102:Lectins; D008081:Liposomes; D037121:Plant Lectins; C017707:Ricinus communis agglutinin-1; D003208:Concanavalin A; D005677:G(M1) Ganglioside; C018835:asialo GM1 ganglioside; D004134:Dimyristoylphosphatidylcholine