The red cell membrane skeleton: recent progress.

I T IS WIDELY believed that the lipid bilayer of the erythrocyte membrane is supported by an elaborate infrastructure of protein molecules that give it viscoelastic properties. The proteins that provide this function are popularly referred to as the “membrane skeleton.” This membrane skeleton is considered to be distinct from the so-called “cytoskeleton,” a term used by cell biologists to describe the complex array of tubes and fibers that connect different parts of cells to each other and to the membrane. In most cells the cytoskeleton is clearly involved with the maintenance of cell shape and probably also plays a role in cell movement. It is assumed that connections exist between the cytoskeleton and the membrane skeleton in cells that have both, but nonnucleated red cells rely solely on the membrane skeleton to confer shape and stability. Perhaps for this reason, membrane skeletons of red cells are elaborately engineered, multiprotein complexes.