Membrane protein phosphorylation during stomatocyte-echinocyte transformation of human erythrocytes

• Published in: Biochimica et biophysica acta Vol. 862; no. 1; pp. 1 - 7
• Main Authors: REINHART, W. H, SUNG, L. A, SCHUESSLER, G. B, SHU CHIEN
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 06.11.1986; North-Holland
• Subjects: Applied sciences; Aspirin - pharmacology; Biological and medical sciences; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; Chlorpromazine - pharmacology; Erythrocytes - cytology; Erythrocytes - drug effects; Erythrocytes - metabolism; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Humans; In Vitro Techniques; Membrane Proteins - metabolism; Molecular and cellular biology; Other techniques and industries; Phosphorylation; Proteins; Vertebrata; Blood cell; Mammalia; Plasma membrane; Red blood cell; Metabolism
• ISSN: 0006-3002; 1878-2434
• DOI: 10.1016/0005-2736(86)90462-1

The normal, discoid shape of red blood cells represents an equilibrium between two opposing factors, i.e., stomatocytic and echinocytic transformations. Most stomatocytic agents were found to be inhibitors of calmodulin, a regulator of the phosphorylation of membrane proteins. We determined whether red cell shape transformations could be caused by changes in phosphorylation of membrane proteins, specifically the cAMP-dependent phosphorylation of ankyrin and band 4.1. Red blood cells were incubated with 32P and 100 microM chlorpromazine (stomatocytic transformation) or 30 mM sodium salicylate (echinocytic transformation) for various time intervals. Ghost membrane proteins were examined by polyacrylamide gel electrophoresis and autoradiography. Spectrin (beta-chain), ankyrin, band 3, band 4.1 and 4.9 were phosphorylated. No change was found in the degree and pattern of phosphorylation after stomatocytic transformation. Salicylate caused a reversible inhibition of transmembranous phosphate transport in both directions. The results indicate that the stomatocytic transformation induced by chlorpromazine and the echinocytic transformation induced by salicylate do not involve a change in phosphorylation, but that the echinocytic transformation induced by salicylate is associated with an inhibition of transmembranous transport of phosphate. Studies with salicylate suggest that the phosphorylation sites of band 3 are found mainly on the endofacial side of the membrane.