Protein kinase C inhibits the Ca(2+)-dependent stimulation of phospholipase C-beta 1 in vitro.
Protein kinase C (PKC) inhibited the Ca(2+)-dependent stimulation of a 600-fold purified phospholipase C beta 1 (PLC-beta 1). Inhibition by PKC was time-dependent, and required ATP and diacylglycerol. Inhibition was more pronounced when the PLC assay was conducted with a PIP2 substrate mixture containing phosphatidylserine, then with a substrate mixture containing phosphatidyle-thanolamine. Cyclic AMP-dependent protein kinase A did not inhibit PLC-beta 1 activity. PKC did not affect the rate of PLC-beta 1 activation by Ca2+ or the rate of PLC-beta 1 deactivation by EGTA. PLC-beta 1 purified 1700-fold was less sensitive to inhibition by PKC despite stoichiometric phosphorylation. These results demonstrate that PKC inhibits the Ca(2+)-dependent stimulation of a 600-fold purified PLC-beta 1 in vitro. Furthermore, purification of PLC-beta 1 to homogeneity results in a diminished sensitivity to inhibition by PKC, indicating that other components may participate in mediating the effect of PKC on the Ca(2+)-dependent stimulation of PLC-beta 1 in vitro.
Litosch
I
I
Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, FL 33101, USA.
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D004075:Diglycerides; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054799:Phospholipase C beta; D010766:Phosphorylation; D011493:Protein Kinase C / Q000494:pharmacology*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D004075:Diglycerides; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D010738:Type C Phospholipases; D054799:Phospholipase C beta; D002118:Calcium