Dual modulation of hepatic and intestinal acyl-CoA: cholesterol acyltransferase activity by (de-)phosphorylation and substrate supply in vitro.
Acyl-CoA: cholesterol acyltransferase (ACAT) activity in microsomes from rat liver and rat intestinal epithelial cells was increased by incubation of the microsomes with the 100 000 x g supernatant fraction in the presence of ATP/MgCl2 and NaF. The measured activity was further increased by including cholesterol-rich liposomes in the preincubation. The ACAT activity in rat liver microsomes could be inhibited by preincubation in the presence of 100 000 x g supernatant and MgCl2 and microsomes preactivated by ATP/MgCl2 could also be inhibited in this way. The results suggest that ACAT activity in vitro is modulated by substrate supply and also reversibly by an ATP-dependent process which may be protein phosphorylation.
D000217:Acyltransferases / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002784:Cholesterol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004848:Epithelium / Q000201:enzymology; D007422:Intestines / Q000201:enzymology*; D008081:Liposomes / Q000494:pharmacology; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008861:Microsomes / Q000201:enzymology*; D008862:Microsomes, Liver / Q000201:enzymology*; D010766:Phosphorylation; D051381:Rats; D012969:Sodium Fluoride / Q000494:pharmacology; D002785:Sterol O-Acyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*
D008081:Liposomes; D015636:Magnesium Chloride; D000255:Adenosine Triphosphate; D012969:Sodium Fluoride; D002784:Cholesterol; D000217:Acyltransferases; D002785:Sterol O-Acyltransferase; D008274:Magnesium