The subunit composition of two high molecular weight extrinsic proteins from human erythrocyte membranes

Purified hollow cylinder (22.5 S) and torus protein (9.0 S) from human erythrocyte membranes, together with the intact membranes, have been dissociated using 2% sodium dodecyl sulphate and electrophoresed in the presence of 0.1% sodium dodecyl sulphate. The torus protein gives rise to a single subunit migrating slightly ahead of band 8 of the polypeptide profile of the intact membranes (Mr approximately 20 000) and the hollow cylinder gives rise to two main subunits, which migrate slightly behind that of the torus protein. It is clearly shown that neither protein is related to erythrocyte membrane spectrin (bands 1 + 2) or actin (band 5).