Inhibition of protein kinase C phosphorylation by mono- and divalent cations.
The effect of a matrix of concentrations of Ca2+ (0.01, 0.1, 0.5, 5 mM), Mg2+ (0.2, 0.5, 1, 2, 5, 10 mM), and Na+ (50, 100, 150 mM) on the phosphorylation of histone H-1 by protein kinase C was measured in the presence of 5 mol % diacylglycerol and Mg-ATP in both phosphatidylserine micelles and liposomes formed from a 1:4 mixture of phosphatidylserine and phosphatidylcholine. Monovalent cations (150 mM) reduced activity by 60 and 84% in the micelle and liposome assay systems, respectively. Inhibition was also observed with 5 mM Ca2+ and 10 mM Mg2+. The phosphorylating activity was compared with computer calculations of the negative electrostatic potentials (psi o) of the phospholipid membranes in the presence of the cations.
Trudell
J R
JR
Department of Anesthesia, Stanford University, CA 94305-5117.
Costa
A K
AK
Csernansky
C A
CA
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D008081:Liposomes; D008274:Magnesium / Q000494:pharmacology*; D008823:Micelles; D009994:Osmolar Concentration; D010718:Phosphatidylserines; D010766:Phosphorylation; D010767:Phosphorylcholine; D011188:Potassium / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats
D008081:Liposomes; D008823:Micelles; D010718:Phosphatidylserines; D010767:Phosphorylcholine; D011493:Protein Kinase C; D008274:Magnesium; D011188:Potassium; D002118:Calcium