J. Biol. Chem., Vol. 255, Issue 2, 441-444, 01, 1980
A new mechanism of regulation of rat liver acetyl-CoA carboxylase activity
MN Abdel-Halim and JW Porter
A factor has been found in rat liver supernatant solution which inhibits
acetyl-CoA carboxylase activity regardless of the presence or absence of
Mg2+ and ATP. Inactivation of the enzyme has been demonstrated via
radiochemical and spectrophotometric assay procedures. The inactivation of
acetyl-CoA carboxylase is not attributable to either malonyl-CoA
decarboxylase activity, to phosphorylation of the enzyme, or to action on
substrates or cofactors of the reaction. The activity of the inhibitor is
destroyed by heating to 70-80 degrees C for 5 min or by treatment with
trypsin. Dialyzing the inhibitor for 24 h at 4 degrees C does not alter its
activity in inhibiting acetyl-CoA carboxylase. Hence, it appears that the
inhibitor is a regulatory protein that acts directly on acetyl-CoA
carboxylase.