Document Detail

Evidence that insulin activates fat-cell acetyl-CoA carboxylase by increased phosphorylation at a specific site.
MedLine Citation:
PMID:  6123319     Owner:  NLM     Status:  MEDLINE    
1. A new rapid method for the purification of fat-cell acetyl-CoA carboxylase is described; the key step is sedimentation after specific polymerization by citrate. 2. Incubation of epididymal fat-pads or isolated fat-cells with insulin or adrenaline leads to a rapid increase or decrease respectively in the activity of acetyl-CoA carboxylase measured in fresh tissue extracts. The persistence of the effect of insulin through high dilution of tissue extracts and through purification involving precipitation with (NH4)2SO4 suggests that the enzyme undergoes a covalent modification after exposure of intact tissue to the hormone. The opposed effects of insulin and adrenaline are not adequately explained through modification of a common site on acetyl-CoA carboxylase, since these hormones bring about qualitatively different alterations in the kinetic properties of the enzyme measured in tissue extracts. 3. The state of phosphorylation of acetyl-CoA carboxylase within intact fat-cells exposed to insulin was determined, and results indicate a small but consistent rise in overall phosphorylation of the Mr-230000 subunit after insulin treatment. 4. Acetyl-CoA carboxylase from fat-cells previously incubated in medium containing [32P]phosphate was purified by immunoprecipitation and then digested with performic acid and trypsin before separation of the released phosphopeptides by two-dimensional analysis. Results obtained show that the exposure of fat-cells to insulin leads to a 5-fold increase in incorporation of 32P into a peptide which is different from those most markedly affected after exposure of fat-cells to adrenaline. 5. These studies indicate that the activation of acetyl-CoA carboxylase in cells incubated with insulin is brought about by the increased phosphorylation of a specific site on the enzyme, possibly catalysed by the membrane-associated cyclic AMP-independent protein kinase described by Brownsey, Belsham & Denton [(1981) FEBS Lett. 124, 145-150].
R W Brownsey; R M Denton
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Biochemical journal     Volume:  202     ISSN:  0264-6021     ISO Abbreviation:  Biochem. J.     Publication Date:  1982 Jan 
Date Detail:
Created Date:  1982-07-08     Completed Date:  1982-07-08     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2984726R     Medline TA:  Biochem J     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  77-86     Citation Subset:  IM    
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MeSH Terms
Acetyl-CoA Carboxylase / isolation & purification,  metabolism*
Adipose Tissue / cytology,  drug effects,  enzymology*
Binding Sites / drug effects
Enzyme Activation / drug effects
Epinephrine / pharmacology
Insulin / pharmacology*
Ligases / metabolism*
Rats, Inbred Strains
Reg. No./Substance:
11061-68-0/Insulin; 51-43-4/Epinephrine; EC 6.-/Ligases; EC Carboxylase

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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