Insulin inhibits the phosphorylation of the membrane cytoskeletal protein spectrin in pig erythrocytes.

Incubation of either ghost membranes with 32P- -ATP or intact erythrocytes with 32P-inorganic phosphate led to phosphorylation of the beta-chain of the major membrane-associated protein spectrin. This phosphorylation was reduced by 30% by insulin (10-100 microU/ml) both in membranes and in intact cells. The results show that the membrane-cytoskeleton is responsive to extracellular signals such as hormone receptor activation.