In vitro regulation of 3-hydroxy-3-methylglutarylcoenzyme a reductase and acylcoenzyme a: Cholesterol acyltransferase activities by phoshorylation-dephosphorylation in rabbit intestine
| Autor: | F. Jeffrey Field, Satya N. Mathur, Bernhard Henning |
|---|---|
| Rok vydání: | 1984 |
| Předmět: |
Male
Phosphatase Sterol O-acyltransferase Magnesium Chloride Biophysics Oleic Acids Reductase Biochemistry Dephosphorylation Acyl-CoA chemistry.chemical_compound Adenosine Triphosphate Microsomes Animals Magnesium Phosphorylation Molecular Biology Hydroxymethylglutaryl-CoA reductase Molecular biology Intestines Bucladesine chemistry Microsome Sodium Fluoride Alkaline phosphatase Hydroxymethylglutaryl CoA Reductases lipids (amino acids peptides and proteins) Cholesterol Esters Rabbits Oleic Acid Sterol O-Acyltransferase |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - General Subjects. 802:9-16 |
| ISSN: | 0304-4165 |
| DOI: | 10.1016/0304-4165(84)90027-8 |
| Popis: | The regulation of 3-hydroxy-3-methylglutarylcoenzyme A reductase and acylcoenzyme A: cholesterol acyltransferase activities by phosphorylation-dephosphorylation in rabbit intestine was studied in vitro. Preparing intestinal microsomes in the presence of 50 mM NaF caused a 64% decrease in the reductase activity. It had no effect on acyl-CoA: cholesterol acyltransferase activity. Microsomes that were prepared in NaF were incubated with intestinal cytosol, a partially purified phosphatase from cytosol, and Escherichia coli alkaline phosphatase. All three preparations increased 3-hydroxy-3-methylglutaryl-CoA reductase by two- or three-fold suggesting dephosphorylation and ‘reactivation’ of enzyme activity. Cytosol caused a 78% increase in acyl-CoA: cholesterol acyltransferase activity, but neither the partially purified phosphatase nor the E. coli alkaline phosphatase affected the acyltransferase activity. Microsomes incubated with increasing concentrations of MgCl2 and ATP decreased both the activities of 3-hydroxy-3-methylglutaryl-CoA reductase and acylcoenzyme A: cholesterol acyltransferase in a step-wise fashion. Whereas this inhibitory effect was specific for reductase, the effect on acyl-CoA: cholesterol acyltransferase activity was secondary to the presence of ATP in the assay mixture. The 8500×g supernatant of intestinal whole homogenate from isolated intestinal cells or scraped mucosa was incubated with MgCl2, ATP and NaF. In microsomes prepared from this supernatant, the activity of 3-hydroxy-3-methylglutaryl-CoA reductase was significantly decreased. Again, no change was observed in the acyltransferase activity. The rate of cholesterol esterification in isolated intestinal cells was not affected by 0.1 mM cAMP or 50 mM NaF. We conclude that under conditions which regulate 3-hydroxy-3-methylglutaryl-CoA reductase activity in rabbit intestine by phosphorylation-dephosphorylation, no regulation of acyl-CoA: cholesterol acyltransferase activity is observed. |
| Databáze: | OpenAIRE |
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