A wortmannin-sensitive and insulin-stimulated protein kinase (WISK), which phosphorylates and activates cardiac 6-phosphofructo-2-kinase (PFK-2), was partially purified from perfused rat hearts. Immunoblotting showed that WISK was devoid of protein kinase B (PKB), serum- and glucocorticoid-regulated protein kinase and protein kinase Cζ (PKCζ). Comparison of the inhibition of WISK, PKCα and PKCζ by different protein kinase inhibitors suggested that WISK was not a member of the PKC family. In addition, WISK contained no detectable phosphoinositide-dependent protein kinase-1 (PDK1) activity. WISK phosphorylated recombinant heart PFK-2 in a time-dependent manner to the extent of 0.4 mol of phosphate incorporated/mol of enzyme subunit, and increased the Vmax of PFK-2 twofold, without affecting the Km for fructose 6-phosphate. WISK phosphorylated Ser-466 to a greater extent than Ser-483 in recombinant heart PFK-2, and both sites were demonstrated to be phosphorylated to the same extent by PKB. Gel filtration and in-gel kinase analysis indicated that WISK was a monomer with a Mr of 56500. Treatment of WISK with protein phosphatase 2A (PP2A) catalytic subunits reversed the effect of insulin, suggesting the involvement of an upstream activating kinase. Indeed, PDK1 was able to partially reactivate the PP2A-treated WISK and this reactivation was not enhanced by PtdIns(3,4,5)P3-containing vesicles. Moreover, a single 57000-Mr band was labelled on incubation of the dephosphorylated WISK preparation with PDK1 and [γ-32P]ATP. These findings provide evidence for the existence of a new protein kinase in the insulin signalling pathway, probably downstream of PDK1.
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Research Article|
March 27 2000
Partial purification and characterization of a wortmannin-sensitive and insulin-stimulated protein kinase that activates heart 6-phosphofructo-2-kinase
Johan DEPREZ;
Johan DEPREZ
*Hormone and Metabolic Research Unit, Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate, 75, 1200 Brussels, Belgium
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Luc BERTRAND;
Luc BERTRAND
*Hormone and Metabolic Research Unit, Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate, 75, 1200 Brussels, Belgium
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Dario R. ALESSI;
Dario R. ALESSI
†MRC Protein Phosphorylation Unit, Department of Biochemistry, University of Dundee, Dundee DD1 4HN, Scotland, U.K.
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Ulrike KRAUSE;
Ulrike KRAUSE
*Hormone and Metabolic Research Unit, Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate, 75, 1200 Brussels, Belgium
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Louis HUE;
Louis HUE
*Hormone and Metabolic Research Unit, Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate, 75, 1200 Brussels, Belgium
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Mark H. RIDER
Mark H. RIDER
1
*Hormone and Metabolic Research Unit, Institute of Cellular Pathology and Université catholique de Louvain, Avenue Hippocrate, 75, 1200 Brussels, Belgium
1To whom correspondence should be addressed (e-mail rider@;horm.ucl.ac.be).
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Publisher: Portland Press Ltd
Received:
August 27 1999
Revision Received:
January 20 2000
Accepted:
January 27 2000
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 2000
2000
Biochem J (2000) 347 (1): 305–312.
Article history
Received:
August 27 1999
Revision Received:
January 20 2000
Accepted:
January 27 2000
Citation
Johan DEPREZ, Luc BERTRAND, Dario R. ALESSI, Ulrike KRAUSE, Louis HUE, Mark H. RIDER; Partial purification and characterization of a wortmannin-sensitive and insulin-stimulated protein kinase that activates heart 6-phosphofructo-2-kinase. Biochem J 1 April 2000; 347 (1): 305–312. doi: https://doi.org/10.1042/bj3470305
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