Calcium- and cyclic AMP-regulated protein kinases of bovine central-nervous-system myelin.
Bovine central-nervous-system myelin was found to contain both Ca2+-activated and cyclic AMP-dependent protein kinases. Each enzyme possesses unique solubility and substrate-specificity characteristics. The Ca2+-activated enzyme, like its substrate (basic protein), is probably deeply embedded in the neural membrane, whereas the cyclic AMP-dependent kinase appears to be much less tightly associated with myelin. Treatment of insoluble myelin fraction housing the Ca2+-activated kinase with phospholipase A2 and phospholipases A2 + C causes a decrease in its ability to become activated by Ca2+. This can be countered by phosphatidylserine and phosphatidylethanolamine. Whereas the activity of the Ca2+-activated membrane-associated kinase is inhibited by chlorpromazine, dibucaine, melittin and Triton X-100, it is activated by certain phorbol diesters (4 beta-phorbol 12-myristate 13-acetate, 4 beta-phorbol 12,13-didecanoate, 4 beta-phorbol 12,13-dibenzoate and 4 beta-phorbol 12,13-diacetate), which appear to exert this effect by lowering the concentration of Ca2+ normally required for the activation of this enzyme. Together these results suggest that the activation of the membrane-associated kinase by Ca2+ most probably requires certain lipids, perhaps those already present in the membrane.
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002417:Cattle; D000242:Cyclic AMP / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D066298:In Vitro Techniques; D009186:Myelin Sheath / Q000201:enzymology*; D010703:Phorbol Esters / Q000494:pharmacology; D010740:Phospholipases / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D012995:Solubility; D013379:Substrate Specificity
D002147:Calmodulin; D010703:Phorbol Esters; D010743:Phospholipids; D047428:Protein Kinase Inhibitors; D000242:Cyclic AMP; D011494:Protein Kinases; D010740:Phospholipases; D002118:Calcium