Endogenous modulation of protein kinase C in the rhesus monkey corpus luteum.
The activity of protein kinase C (PKC) and the presence of endogenous PKC-modulatory factors in monkey CL have not been previously reported. The specific activity of Ca(2+)- and lipid-dependent PKC activity in cytosols prepared from CL obtained from rhesus monkeys at midluteal phase was 515.1 +/- 79 pmol/min x mg; Ca(2+)-independent PKC activity was 233.2 +/- 31 pmol/min x mg. No PKC-inhibitory activity was seen when luteal cytosol was mixed with a control preparation of PKC (control PKC 10.2 +/- 2.0 pmol/min; luteal cytosol plus control PKC 26.0 +/- 2.1 pmol/min). However, the monkey CL contained PKC-phosphatase activity (the endogenous inhibitor of PKC in the rat ovary is a protein phosphatase). Specific activity of luteal PKC phosphatase activity was 609.0 +/- 94 pmol/min x mg. Kinetic studies suggested that the monkey CL contained a competitive inhibitor of the phosphatase. Heat-treated cytosol mixed with control PKC (9.0 +/- 0.7 pmol/min) resulted in enzyme activity that was significantly greater than that of the control (13.7 +/- 1.2 pmol/min). Luteal cytosol that had been heat-treated and extracted with petroleum ether substituted for lipids in the activation of PKC. In summary, the activity of PKC in the monkey CL was readily measurable; it was not masked by an endogenous PKC-inhibitory factor. The monkey CL did contain a heat-stable PKC-stimulatory activity.
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K M
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Department of Physiology and Pharmacology, University of South Dakota, School of Medicine, Vermillion 57069-2390.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003338:Corpus Luteum / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004075:Diglycerides / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006358:Hot Temperature; D007700:Kinetics; D008055:Lipids / Q000494:pharmacology; D008253:Macaca mulatta; D010053:Ovary / Q000201:enzymology; D010718:Phosphatidylserines / Q000494:pharmacology; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats
D004075:Diglycerides; D008055:Lipids; D010718:Phosphatidylserines; D004533:Egtazic Acid; D011493:Protein Kinase C; D010749:Phosphoprotein Phosphatases; D002118:Calcium