Structure of the cell surface.

The cell surface is the locus for many important biochemical functions of cells and for the interactions of cells with one another and with their environment. The structure of the cell surface may be thought of as three-layered, with a central plasma membrane to which certain macromolecular components are attached on the outer face (the exoskeleton) and other components on the inner face (the membrane cytoskeleton). In the last decade, the basic molecular structure of the plasma membrane has been elucidated and can be represented by the fluid mosaic model as a first approximation. The binding of specific integral proteins of the membrane to individual peripheral proteins outside or inside the cell is most likely the basis for the three-layered structure of the cell surface. Studies of the last several years on the molecular structures of these three-layered cell surfaces of cultured normal fibroblasts and of fibroblasts transformed by oncogenic viruses are beginning to shed light on the molecular mechanisms responsible for changes in cell shape, adhesiveness, and in contact inhibition of motility associated with neoplastic transformation.