The roles of different protein kinases and of calmodulin in the effects of Ca2+ mobilization on 3-hydroxy-3-methylglutaryl-CoA reductase activity in isolated rat hepatocytes.
The roles of protein kinase C, Ca2+/calmodulin-dependent protein kinase and AMP-activated protein kinase in the phosphorylation of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase induced by Ca2(+)-mobilizing conditions in isolated hepatocytes were investigated. Only partial evidence for the involvement of AMP-activated kinase was found. Antagonism of calmodulin action prolonged the decrease in expressed/total activity ratio induced by vasopressin plus glucagon. Protease inhibitors active against Ca2(+)-dependent cytosolic proteases or lysosomal proteolysis did not attenuate the loss of total HMG-CoA reductase induced by glucagon plus vasopressin, but calmodulin antagonists largely prevented this effect.
Zammit
V A
VA
Hannah Research Institute, Ayr, Scotland, U.K.
Caldwell
A M
AM
D000249:Adenosine Monophosphate / Q000378:metabolism; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation; D005260:Female; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism*; D008099:Liver / Q000201:enzymology*; D011480:Protease Inhibitors / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013379:Substrate Specificity
D002147:Calmodulin; D011480:Protease Inhibitors; D000001:Calcimycin; D000249:Adenosine Monophosphate; D006903:Hydroxymethylglutaryl CoA Reductases; D011494:Protein Kinases; D011493:Protein Kinase C; D002118:Calcium