Calcium-activated phospholipid-dependent protein kinases from rat liver: characterization of purified isoenzymic forms.
1. This report describes characteristics of the three isoenzymic forms of protein kinase C purified in our laboratory from rat liver. 2. All three C-kinases phosphorylated several histone preparations, and to a much lesser degree, other protein substrates and had similar Km values for ATP and histones. 3. Each isoenzyme demonstrated an absolute requirement for Ca2+ and negatively charged phospholipids. 4. Among various phospholipids tested, phosphatidylserine from bovine brain was most effective with approximately 220 fold stimulation over basal activity. 5. Both diolein and 12-O-tetradecanoylphorbol-13-acetate decreased the Ca2+ requirement of the isoenzymes and also directly stimulated C-II and C-III enzymes in the presence of suboptimal concentrations of Ca2+ and phosphatidylserine.
Azhar
S
S
Department of Medicine, Stanford University School of Medicine, Palo Alto, CA 94304.
Butte
J
J
Reaven
E
E
D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D007527:Isoenzymes / Q000302:isolation & purification*; D008099:Liver / Q000201:enzymology*; D010743:Phospholipids / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000302:isolation & purification*; D051381:Rats; D013379:Substrate Specificity
D004075:Diglycerides; D006657:Histones; D007527:Isoenzymes; D010743:Phospholipids; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D011493:Protein Kinase C; D002118:Calcium; C013965:diolein