Spectrin binding and the control of membrane protein mobility.

Transmembrane proteins of the human erythrocyte show restricted in-plane mobility. Many of the restrictions on mobility are attributable to the molecules of spectrin which are located on the protoplasmic surface of the erythrocyte membrane. These molecules are elongate, form end-to-end heterodimer associations, and bind selectively to protein (or proteins) accessible on inside-out, but not right-side out, membrane vesicles.