title: Protein kinase C of human erythrocytes phosphorylates bands 4.1 and 4.9.
abstract: Addition of 10 nM 12-O-tetradecanoylphorbol 13-acetate (TPA) to intact human erythrocytes results in rapid phosphorylation of two cytoskeletal components, bands 4.1 and 4.9. The synthetic diacylglycerol, 1-oleoyl-2-acetylglycerol, shows a similar effect, while the biologically inactive phorbol ester, 4 alpha-phorbol didecanoate, fails to enhance phosphorylation. That TPA and 1-oleoyl-2-acetylglycerol stimulate this phosphorylation suggests that protein kinase C is being activated. In the presence of TPA, bands 4.1 and 4.9 incorporate 1.5 mol Pi/mol protein and 1.2 mol Pi/mol protein, respectively. The pattern and extent of phosphorylation shows that it is not due to cAMP-dependent protein kinases, which also phosphorylate bands 4.1 and 4.9. Ca2+-phospholipid-dependent protein kinase activity is demonstrable in the soluble fraction of erythrocytes, and has been partially purified (2200-fold) from the hemolysate by affinity chromatography (Uchida and Filburn, 1984. J. Biol. Chem. 259, 12311-12314). The affinity purified erythrocyte kinase has a 42 A Stokes' radius and phosphorylates purified bands 4.1 and 4.9 in vitro in a Ca2+- and phospholipid-dependent manner. These results show that human erythrocytes contain protein kinase C, and that band 4.1 and 4.9 are the major endogenous substrates for this kinase.
mesh_terms: D001798:Blood Proteins / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000097:blood*; D004075:Diglycerides / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009479:Neuropeptides; D010750:Phosphoproteins / Q000097:blood*; D011493:Protein Kinase C / Q000097:blood* / Q000302:isolation & purification; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D001798:Blood Proteins; D003598:Cytoskeletal Proteins; C044805:DMTN protein, human; D004075:Diglycerides; D008565:Membrane Proteins; D008840:Microfilament Proteins; D009479:Neuropeptides; D010750:Phosphoproteins; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D000242:Cyclic AMP; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate