An insulin-stimulated ribosomal protein S6 kinase from rabbit liver

• Published in: The Journal of biological chemistry Vol. 264; no. 31; pp. 18397 - 18401
• Main Authors: Gregory, J S, Boulton, T G, Sang, B C, Cobb, M H
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05-11-1989; American Society for Biochemistry and Molecular Biology
• Subjects: Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Calcium-Calmodulin-Dependent Protein Kinases; Chromatography; Electrophoresis, Polyacrylamide Gel; Enzyme Activation - drug effects; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; insulin; Insulin - pharmacology; liver; Liver - enzymology; Molecular Weight; Phosphoprotein Phosphatases - pharmacology; Phosphorylation; Protein Kinases - isolation & purification; Protein Kinases - metabolism; Protein Kinases - pharmacology; Protein Phosphatase 2; Rabbits; Ribosomal Protein S6 Kinases; Transferases; Vertebrata; Phosphorylation; Mammalia; Enzymatic activity; Radiolabelling; Enzyme; Protein kinase; Liver; Rabbit; Activation; Lagomorpha; Ion exchange chromatography
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)51478-2

In this report we describe an activated form of S6 protein kinase in rabbits treated acutely with insulin. The major insulin-stimulated activity in rabbit liver is increased 2- to 5-fold compared to material from untreated animals based on DEAE-cellulose profiles. The activity observed in DEAE-cellulose fractions can be separated into a major and a minor peak, each having very similar chromatographic behavior. Chromatography on DEAE-cellulose, S-Sepharose, heptyl-Sepharose, heparin-agarose, and Mono Q results in greater than 20,000-fold purification of the insulin-stimulated enzyme with a 12% recovery. The stimulated activity has chromatographic properties similar to an S6 protein kinase studied previously in 3T3-L1 cells (Cobb, M. H. (1986) J. Biol. Chem. 261, 12994–12999) and other systems. The enzyme purified from insulin-treated animals contains a major band that migrates in sodium dodecyl sulfate-polyacrylamide gels with Mr ≃ 70,000; this band also appears in the control preparation. Treatment of the insulin-stimulated S6 kinase with the catalytic subunit of phosphatase 2a reduces its activity by 97%. The activity of the inactivated S6 kinase is stimulated nearly 5-fold by a 15-min preincubation with partially purified insulin-stimulated microtubule-associated protein-2 kinase.