Retinal inhibits TPA activated, calcium-dependent, phospholipid-dependent protein kinase ("C" kinase).
RAW264 macrophage-like cells contain a kinase which is dependent on Ca++ and phosphatidylserine for activity (C kinase) and is stimulable by the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate. Retinal inhibits the activity of the tumor promoter-activated kinase in a concentration-dependent manner. The apparent Ki for inhibition is 1 X 10(-5)M. Retinal is not a general inhibitor of phosphotransferase reactions as it did not inhibit the activity of purified cyclic AMP-dependent protein kinase. It is possible, therefore, that the action of retinoids to antagonize tumor promoter effects on cell function may be mediated at the level of regulation of C-kinase.
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D008264:Macrophages / Q000201:enzymology; D010718:Phosphatidylserines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D012172:Retinaldehyde / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000037:antagonists & inhibitors; D014801:Vitamin A / Q000031:analogs & derivatives*
D010718:Phosphatidylserines; D047428:Protein Kinase Inhibitors; D014801:Vitamin A; D013755:Tetradecanoylphorbol Acetate; D012172:Retinaldehyde; D002118:Calcium