Red cell membrane cytoskeleton and the control of membrane properties.

Introduction The material properties of the red cell membrane, in particular its unique stability towards shearing forces and its elasticity with respect to linear deformation, result from the interaction of the phospholipid bilayer with the membrane cytoskeleton that covers its cytoplasmic surface. When this protein network is extracted or destroyed by proteolysis the membrane spontaneously vesiculates. The pathways through which the proteins exert their effects on the membrane properties are not known. Three types of interaction between the membrane and the membrane cytoskeleton can be identified, namely bridging of spectrin to band 3, the major transmembrane protein, by ankyrin [ 11, binding of protein 4.1 to one or more integral membrane proteins (see below), and a weak, but globally important, direct association between cytoskeletal protein and phospholipid, almost certainly phosphatidylserine [2, 31. We consider here only the protein-protein interactions and the manner in which they might regulate the membrane properties.