Action of insulin and catecholamines on the phosphorylation of proteins associated with the cytosol, membranes, and “fat cake” of rat fat cells.

作者：W.B. Benjamin, Nicola Clayton · 发表于：Journal of Biological Chemistry · 年份：1978 · DOI：10.1016/s0021-9258(17)34922-0 · 被引用次数：60 · 研究领域：Lipid metabolism and biosynthesis、Diet, Metabolism, and Disease、Biochemical Analysis and Sensing Techniques

Hormone-induced phosphoprotein phosphorylations were studied in isolated rat fat cells and in subcellular fractions derived from fat cells.Insulin action increased the phosphorylation of two phosphoproteins designated 2 and fib, the molecular weights of which are 130,000 and 62,000, respectively.Epinephrine and isoproterenol action decreased the phosphorylation of phosphoprotein-6b and markedly increased the phosphorylation of phosphoprotein-5, the molecular weight of which is approximately 65,000 to 70,000.Changes in the phosphorylations of phosphoproteins-5 and -6b and fat cell glycerol production varied as a function of epinephrine concentrations.Isoproterenol-induced phosphoprotein-6b dephosphorylation was studied in "cold chase" experiments.At each time point of the "cold chase" isoproterenol increased the dephosphorylation of phosphoprotein-6band increased the phosphorylation of phosphoprotein-5.N-Ethylmaleimide at 0.1 mM inhibited fat cell protein phosphorylation 35%.However, it inhibited specifically phosphoprotein-6b phosphorylation and increased phosphoprotein-5 phosphorylation relative to other protein phosphorylations.Periodic acid-Schiff stain of gel electrophoretograms containing fat cell proteins showed that radiolabeled phosphoproteins-3 and -4 were glycoproteins.Subcellular fractionation of :'2P-labeled fat cells demonstrated that phosphoprotein-2 was found with the cytosol fraction, while phosphoproteins-4 and -6a were present in the "crude membrane" fractio...