[The constituents of the red cell membrane (author's transl)]

Erythrocyte plasma membrane consists of lipids, proteins and carbohydrates. The major lipids are phosphoglycerolipids which are amphiphatic molecules and which are responsible for the double layer structure of the membrane. Both membrane leaflets are fluid structures. Lipids diffuse laterally with great velocity. Exchange of lipids between the leaflets hardly occurs. The external leaflet can readily exchange phospholipids and cholesterol with the plasma. The external and the internal leaflets have a different composition. Major proteins are identified by polyacrylamide gel electrophoresis while enzyme proteins are detected through their catalytic properties. Membrane proteins play many roles, among which are the maintenance of red cell shape and deformability (spectrin), cation and anion transport, intra- and extracellular metabolisms. Proteins penetrate more or less deeply into the lipid double layer. Their lateral mobility is limited. Sugars are covalently bound to various lipids and proteins. Being present only on the external surface of the membrane, they are the substrates of blood group antigens. Several abnormalities of erythrocyte membrane constituents have appeared in various congenital hemolytic anemias and in progressive muscular dystrophies.