Investigation by Crossed Immunoelectrophoresis of Membrane-Cytoskeleton Interactions in Human Erythrocyte Membranes

The red blood cell needs a high stability as well as a high deformability and elasticity to be able to pass through the capillaries of the circulation system without being disrupted. These properties are supported by the cytoskeleton of the cell membrane and by its dynamic interactions with membrane spanning proteins and the lipid bilayer. A model for these postulated interactions is shown in Fig. 1: Spectrin (Band 1 and Band 2; nomenclature according to Fairbanks et al.) is linked with the syndeins (Bands 2.1, 2.2., 2.3 and 2.6) which are in turn associated with Band 3, the major integral membrane protein. These interactions are considered as the major forces which anchor the membrane skeleton to the bilayer core. Within the membrane cytoskeleton spectrin (Bands 1 and 2) is believed to form a tetramer which is built up of two heterodimers. The proteins called Band 4.1a and Band 4.1b bind to the ends of these tetramers and connect spectrin to Band 5 (the red cell actin). It has further been postulated that Bands 4.1a and 4.1b are attached to the lipid bilayer, a suggestion which has also been made for spectrin. However, the association sites have not yet been identified.