title: The effects of phorbol ester, diacylglycerol, phospholipase C and Ca2+ ionophore on protein phosphorylation in human and sheep erythrocytes.
abstract: Treatment of human or sheep erythrocytes with PMA (phorbol myristate acetate) enhanced [32P]phosphate labelling of membrane polypeptides of approx. 100, 80 and 46 kDa. The 80 kDa and 46 kDa polypeptides coincided with bands 4.1 and 4.9 respectively on Coomassie-Blue-stained gels. Similar but smaller effects were obtained by treating human cells with 1-oleoyl-2-acetyl-rac-glycerol (OAG), exogenous bacterial phospholipase C or ionophore A23187 + Ca2+, each of which treatments would be expected to raise the concentration of membrane diacylglycerol. In contrast, sheep cells, which do not increase their content of diacylglycerol when treated with phospholipase C or A23187 + Ca2+, only showed enhanced phosphorylation with OAG. Neither human nor sheep cells showed any enhanced [32P]phosphate labelling of phosphoproteins when treated with 1-mono-oleoyl-rac-glycerol. It is concluded that diacylglycerol from a variety of sources can activate erythrocyte protein kinase C, but that the most effective diacylglycerol is that derived from endogenous polyphosphoinositides. In contrast with bacterial phospholipase C and A23187, which stimulate synthesis of phosphatidate by increasing the cell-membrane content of diacylglycerol in human erythrocytes, PMA, OAG or 1-mono-oleoyl-rac-glycerol caused no change in phospholipid metabolism.
mesh_terms: D000818:Animals; D001798:Blood Proteins / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D004075:Diglycerides / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D005989:Glycerides / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007476:Ionophores / Q000494:pharmacology*; D010446:Peptide Fragments / Q000032:analysis; D010704:Phorbols / Q000494:pharmacology*; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D012756:Sheep; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000494:pharmacology*
chemical_list: D001798:Blood Proteins; D004075:Diglycerides; D005989:Glycerides; D007476:Ionophores; D010446:Peptide Fragments; D010704:Phorbols; D010710:Phosphates; D010738:Type C Phospholipases; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium