An insulin-stimulated ribosomal protein S6 kinase from rabbit liver.
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 congruent to 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.
Gregory
J S
JS
Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas 75235.
Boulton
T G
TG
Sang
B C
BC
Cobb
M H
MH
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002845:Chromatography; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D007328:Insulin / Q000494:pharmacology*; D008099:Liver / Q000201:enzymology*; D008970:Molecular Weight; D010749:Phosphoprotein Phosphatases / Q000494:pharmacology; D010766:Phosphorylation; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D054648:Protein Phosphatase 2; D011817:Rabbits; D019893:Ribosomal Protein S6 Kinases
D007328:Insulin; D011494:Protein Kinases; D019893:Ribosomal Protein S6 Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2