Basic protein in brain myelin is phosphorylated by endogenous phospholipid-sensitive Ca2+-dependent protein kinase.
Phosphorylation of myelin basic protein (MBP) in rat or rabbit brain myelin was markedly stimulated by Ca2+, and this reaction was not essentially augmented by exogenous phosphatidylserine or calmodulin or both. Solubilization of myelin with 0.4% Triton X-100 plus 4 mM EGTA, with or without further fractionation, showed that Ca2+-dependent phosphorylation of MBP required phosphatidylserine, but not calmodulin. DEAE-cellulose chromatography of solubilized myelin revealed a pronounced peak of protein kinase activity stimulated by a combination of Ca2+ and phosphatidylserine; a protein kinase stimulated by Ca2+ plus calmodulin was not detected. These findings clearly indicate an involvement of phospholipid-sensitive Ca2+-dependent protein kinase in phosphorylation of brain MBP, although a possible role for the calmodulin-sensitive species of Ca2+-dependent protein kinase in this reaction could not be excluded or established. Phosphorylation of MBP in solubilized rat myelin catalyzed by the phospholipid-sensitive enzyme was inhibited by adriamycin, palmitoylcarnitine, trifluoperazine, melittin, polymyxin B, and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7).
D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology; D002417:Cattle; D004676:Myelin Basic Protein / Q000378:metabolism*; D009186:Myelin Sheath / Q000201:enzymology*; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology*; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains
D002147:Calmodulin; D004676:Myelin Basic Protein; D010718:Phosphatidylserines; D010743:Phospholipids; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases; D002118:Calcium