The Structure and Properties of the Cell Surface Coat

Abstract

This chapter discusses the structure and properties of the cell surface coat. Cell surface coats have been found on all living cells that have been examined with sufficiently sensitive methods. These cells protect their fragile plasma membrane with a relatively strong, hydrophilic coat which is a permanent feature of the cell surface complex. Under special conditions, however, rarely and momentarily, these coats can be breached or even removed from certain cells to reveal the delicate, oily, liquid like layer of the plasma membrane, damage to which is lethal unless immediately repaired. These cells usually are able to replace their missing coats in a matter of minutes. Most animal cell coats appear in the electron microscope (EM) as a uniform layer at the external cell surface. The layer seems to originate at, or be a part of, the outer leaflet of the trilaminar plasma membrane, and usually is 100-200 Å thick. A variety of methods has been developed to reveal the ultrastructure of cell coats, the details of which depend on the particular method employed. The strength or durability of the cell surface coat varies dramatically among various cells. © 1976 Academic Press Inc.