Evidence that insulin activates fat-cell acetyl-CoA carboxylase by increased phosphorylation at a specific site.

摘要: 1. A new rapid method for the purification of fat-cell acetyl-CoA carboxylase is described; key step sedimentation after specific polymerization by citrate. 2. Incubation epididymal fat-pads or isolated fat-cells with insulin adrenaline leads to a increase decrease respectively in activity measured fresh tissue extracts. The persistence effect through high dilution extracts and involving precipitation (NH4)2SO4 suggests that enzyme undergoes covalent modification exposure intact hormone. opposed effects are not adequately explained common site on carboxylase, since these hormones bring about qualitatively different alterations kinetic properties 3. state phosphorylation within exposed was determined, results indicate small but consistent rise overall Mr-230000 subunit treatment. 4. Acetyl-CoA from previously incubated medium containing [32P]phosphate purified immunoprecipitation then digested performic acid trypsin before separation released phosphopeptides two-dimensional analysis. Results obtained show 5-fold incorporation 32P into peptide which those most markedly affected adrenaline. 5. These studies activation cells brought increased enzyme, possibly catalysed membrane-associated cyclic AMP-independent protein kinase described Brownsey, Belsham & Denton [(1981) FEBS Lett. 124, 145-150].