Subcellular distribution of ATP-stimulated and ADP-inhibited acetyl-CoA hydrolase in livers from control and clofibrate-treated rats: comparison of the cytosolic and peroxisomal enzyme.
An extramitochondrial acetyl-CoA hydrolase [EC 3.1.2.1] in the rat liver, which is stimulated by ATP and inhibited by ADP, is known to be extremely cold-labile. During subcellular fractionations at low temperatures (2-4 degrees C), most of the enzyme activity was lost; however, most could be recovered by rewarming at 37 degrees C in the presence of a high concentration of potassium phosphate. This enabled us to measure the activities of cold-treated samples. The majority of the ATP-stimulated and ADP-inhibited acetyl-CoA hydrolase activity in rat livers was detected in the cytosolic fraction and small amounts were detected in the peroxisomal fraction. The activity of peroxisomal ATP-stimulated acetyl-CoA hydrolase was not noticeably increased after clofibrate-treatment. However, the cytosolic activity greatly increased after clofibrate treatment. The activity in the isolated peroxisomal fraction per g of liver was about 5% of that in the cytosolic fraction of liver from the control and about 2% in that from clofibrate-treated rats. Besides having similar nucleotide (ATP and ADP) sensitivity and cold lability, the enzyme protein in the peroxisomal fraction migrated to the same position as the cytosolic acetyl-CoA hydrolase based on Western blot analysis with antibody against purified acetyl-CoA hydrolase from rat liver cytosol. These results suggest that the peroxisomal enzyme and cytosolic enzyme may be the same entity.
Nakanishi
Y
Y
Department of Oncology, Osaka University Medical School.
Okamoto
K
K
Isohashi
F
F
D000104:Acetyl-CoA Hydrolase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000244:Adenosine Diphosphate / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002458:Cell Fractionation; D002994:Clofibrate / Q000494:pharmacology*; D003080:Cold Temperature; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D008830:Microbodies / Q000187:drug effects / Q000201:enzymology*; D051381:Rats
D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000104:Acetyl-CoA Hydrolase; D002994:Clofibrate