In vitro regulation of bovine adrenal cortical acyl-CoA: cholesterol acyltransferase and comparison with the rat liver enzyme.
Acyl-CoA:cholesterol acyltransferase activity in bovine adrenal cortical microsomes was increased by preincubation of microsomes in vitro in the presence of MgCl2. The acyltransferase activity in the microsomes could be inhibited by further incubation in the presence of ATP/MgCl2. These effects appear to complement the known ATP-dependent activation of adrenal cytosolic cholesterol ester hydrolase, which is consistent with the role of the hydrolase in supplying cholesterol for steroidogenesis. These effects are, however, opposite to those recently demonstrated for the rat liver and intestine. Acyl-CoA:cholesterol acyltransferase activity in rat liver can be increased by the addition of cholesterol, as substrate, or by 25-hydroxycholesterol. Such activation was not observed in adrenal microsomal preparations, further suggesting that the mechanisms of regulation of cholesterol esterification differs between these tissues.
D000214:Acyl Coenzyme A / Q000378:metabolism*; D000217:Acyltransferases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D002417:Cattle; D002784:Cholesterol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006888:Hydroxycholesterols / Q000494:pharmacology; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats; D013045:Species Specificity; D002785:Sterol O-Acyltransferase / Q000378:metabolism*
D000214:Acyl Coenzyme A; D006888:Hydroxycholesterols; D015636:Magnesium Chloride; C007997:25-hydroxycholesterol; D000255:Adenosine Triphosphate; D002784:Cholesterol; D000217:Acyltransferases; D002785:Sterol O-Acyltransferase; D008274:Magnesium