Membrane phosphorylation in intact human erythrocytes

Abstract

The time course of 32P incorporation into ATP and monoesterified membrane phosphatases was studied within 1 h of incubation of intact human erythrocytes. Analysis of membrane proteins and phospholipids showed dynamically exchanged phosphates mainly in the phospholipid fraction. The extent of ATP turnover by spectrin band 2 polypeptide phosphorylation was very small. The 32P-ATP and the membrane 32P-phosphate label could be chased via the metabolism by the addition of extracellular Pi. From the relative changes in the specific radioactivity of ATP and of the membrane phosphate in intact erythrocytes we assume that about 60% of the erythrocyte ATP production are linked to the ATP consumption by the rapid polyphosphoinositide turnover. It is conceivable that there is a connection between the protein factors modifying the affinity of (Ca2+, Mg2+)-ATPase and the metabolism of the polyphosphoinositides in the erythrocyte membrane.