Fibronectin–plasma membrane interactions in the adhesion and spreading of hamster fibroblasts

Abstract

GLYCOPROTEINS of the cell surface have been implicated in intercellular adhesion and in the attachment of cells to a growth surface¹. However, the specificity of this role and the possibility of a direct involvement of carbohydrate are poorly understood. We have reported² that some lectin-resistant mutant cells^3,4 defective in the biosynthesis of surface carbohydrates are poorly adhesive to serum- or gelatin-coated cover slips and show low cell–cell aggregation. A major glycoprotein component of serum, fibronectin^5,6 (also called LETS⁷ and Cig⁸), analogous to a glycoprotein of adherent mammalian fibroblasts, has been identified as the active factor enhancing adhesiveness and spreading of cells to plastic and glass^9–13 and collagen films¹⁴. We now report that fibronectins purified⁹ from culture fluids of normal BHK or ricin-resistant (Ric^R) cells mediate the rapid adhesion and spreading of wild-type BHK cells to plastic and to collagen films. By contrast, mutant Ric^R cells deficient in surface carbohydrates respond poorly to fibronectin in adhesion to these substrates.