In vivo modulation of rat liver acyl-coenzyme A:cholesterol acyltransferase by phosphorylation and substrate supply.
Rats were infused intravenously with a bolus of mevalonolactone or cholesterol-rich chylomicron and microsomes prepared from the livers at times up to 2 h after the infusion. Acyl-CoA cholesterol acyltransferase (ACAT) activity was measured in the microsomes under conditions that define the activity state of the enzyme which recent evidence suggests may depend on the degree of phosphorylation of the enzyme. ACAT activity was increased by both treatments. Some of the observed increase could be attributed to an increase in the supply of substrate cholesterol to the enzyme. The remaining change in activity was consistent with a change in the activity state of ACAT occurring in vivo in response to the influx of cholesterol to the enzyme.
D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D002914:Chylomicrons / Q000378:metabolism; D005260:Female; D008798:Mevalonic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D008862:Microsomes, Liver / Q000201:enzymology*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D002785:Sterol O-Acyltransferase / Q000378:metabolism*
D002914:Chylomicrons; C015367:mevalonolactone; D002784:Cholesterol; D000217:Acyltransferases; D002785:Sterol O-Acyltransferase; D008798:Mevalonic Acid