Proceedings of the National Academy of Sciences · 1977 · 85 citations · 20 references
Life SciencesBiochemistryCell BiologyCellular MetabolismMetabolic RegulationMetabolismAcetyl-coa Carboxylase InhibitionFatty Acid BiosynthesisFatty Acid MetabolismFatty Acid SynthesisLipid Biosynthesis InhibitionLipid MetabolismAcetyl-coa Carboxylase EnzymeAcetyl-coa Carboxylase RegulationAcetyl-coenzyme A Carboxylase InhibitionAllosteric Regulation Of Acetyl-coa CarboxylaseAnimal Fatty Acid BiosynthesisDe Novo Fatty Acid SynthesisFatty Acid CatabolismFatty Acid Synthase Inhibition
Labeling experiments with chicken liver cell monolayers and suspensions show that glucagon and N6, O2-dibutyryladenosine 3':5'-cyclic monophosphate (dibutyryl cyclic AMP) block fatty acid synthesis from acetate without appreciably affecting cholesterogenesis from acetate or acylglyceride synthesis from palmitate. Neither acetyl-CoA carboxylase [acetyl-CoA:carbon-dioxide ligase (ADP-forming), EC 6.4.1.2] activity assayed in the presence of citrate nor fatty acid synthetase activity is decreased in extracts of cells treated with glucagon. However, the cytoplasmic concentration of citrate, a required allosteric activator of acetyl-CoA carboxylase, is depressed more than 90% by glucagon or dibutyrl cyclic AMP. Pyruvate or lactate largely prevents the inhibitory action of these effectors on fatty acid synthesis by causing a large increase in cytoplasmic citrate level. Thus, it appears that glucagon, acting via cyclic AMP, inhibits fatty acid synthesis by blocking the formation of citrate, an essential activator of acetyl-CoA carboxylase.
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