Possible roles for the membrane cytoskeleton in regulating red cell stability and deformability.

Several observations suggest the presence of a membrane cytoskeleton in the red cell. Some of these imply possible roles for that cytoskeleton in regulating red cell shape and deformability. One of the most striking examples of this role is that of the spectrin-free spherocyte mouse. In this condition, spectrin is virtually absent from the membranes of erythrocyte cells and osmotic fragility and survival is markedly affected. The mice are afflicted with an extreme haemolytic anaemia which is barely compatible with life. An unequivocal role for the cytoskeleton in being responsible for this disorder has been shown through experiments in which the cytoskeleton has been reconstituted by specific rebinding of normal mouse spectrin to these defective cell membranes. Marked improvement in membrane fragmentation, membrane, membrane fusion, and osmotic stability following reconstitution indicated that these functions are partially regulated through the membrane cytoskeleton, and its predominant protein, spectrin.