FUNCTIONALLY DISTINCT ROLES FOR GLYCOSYLATION OF ALPHA-INTEGRIN AND BETA-INTEGRIN CHAINS IN CELL MATRIX INTERACTIONS

Laminin interaction with gp120/140, a B16-F10 laminin-binding protein immunologically related to alpha6beta1 integrin, has been shown to be dependent on oligosaccharides from both ligand and receptor. Lectin analysis of gp120/140 led to the conclusion that this integrin is a sialoglycoprotein bearing mainly complex antennary structures. By means of exoglycosidase treatment, it was possible to identify alpha-galactosyl residues on the integrin alpha chain as the laminin-binding determinants. These residues are involved in cell adhesion to laminin. On the other hand, beta-chain complex antennary structures, whose synthesis could be inhibited by swainsonine, were associated with cell spreading rather than cell adhesion. Thus, it was possible to modulate integrin-mediated cell adhesion and spreading through changes in the glycosylation state of integrin alpha and beta chains.