Biochemical Determinants of Cell Adhesion

Abstract

This chapter focuses essentially on the biochemistry of cell surface components implicated as the mediators of cell–cell or cell–substrate adhesion. During the past decade, a considerable amount of evidence has been found depicting the importance of cell surface glycoproteins and high molecular weight proteoglycans as the mediators of cell-to-cell and cell-to-substrate adhesion. This evidence is reviewed in the chapter for a wide variety of eukaryotic cell systems, from yeast and sponge cells, as perhaps the simplest, to the much more complex avian and mammalian embryonic cell systems. The emphasis is on a critical analysis of the biochemistry of these determinants. Initial considerations that cellular adhesion resulted from nonspecific interactions via the neutralization of negative charge on cell surfaces or Van der Waals' forces acting over broad areas of surface membrane have now been replaced with the models of cellular adhesion featuring the interaction of specific cell surface proteins and polysaccharides. These models, derived particularly from studies on cell–cell adhesion in simple eukaryotic cells or cell-substrate adhesion in mammalian and avian cells, are based on accumulating experimental evidence and emphasize a specificity of interaction analogous to that of enzyme–substrate, antigen–antibody, and lectin–polysaccharide interactions. There is also suggestive evidence that simple eukaryotic cells adhere by the mechanisms that are biochemically simpler than those found in the much more complex avian and mammalian cells.