[The molecular basis for increased rigidity of the erythrocyte membrane]

The red blood cell membrane is built on a bilayer lipid matrix associated with proteins. Proteins are located either within the bilayer lipid matrix (intrinsic proteins) or are attached to the hydrophilic surfaces of the bilayer lipid matrix (extrinsic proteins). Intrinsic proteins are held in position by a cytoskeleton. Modifications in both membrane lipids or proteins may alter the red blood cell membrane deformability. The role of the following factors, alone or in combination, in increasing the membrane rigidity, is discussed and reviewed: cholesterol/phospholipids ratio, polyunsaturated fatty acids content, phosphatidylethanolamine methylation, increased intracellular Ca++, protein phosphorylation, membrane protein cross-linking and membrane lipid peroxidation.