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Protein phosphatase 2A is the main phosphatase involved in the regulation of protein kinase B in rat adipocytes.

Author:
  • Svante Resjö
  • Olga Göransson
  • Linda Härndahl
  • Stanislaw Zolnierowicz
  • Vincent Manganiello
  • Eva Degerman
Publishing year: 2002
Language: English
Pages: 231-238
Publication/Series: Cellular Signalling
Volume: 14
Issue: 3
Document type: Journal article
Publisher: Elsevier

Abstract english

In adipocytes, protein kinase B (PKB) has been suggested to be the enzyme that phosphorylates phosphodiesterase 3B (PDE3B), a key enzyme in insulin's antilipolytic signalling pathway. In order to screen for PKB phosphatases, adipocyte homogenates were fractionated using ion-exchange chromatography and analysed for PKB phosphatase activities. PKB phosphatase activity eluted as one main peak, which coeluted with serine/threonine phosphatases (PP)2A. In addition, adipocytes were incubated with inhibitors of PP. Incubation of adipocytes with 1 microM okadaic acid inhibited PP2A by 75% and PP1 activity by only 17%, while 1 microM tautomycin inhibited PP1 activity by 54% and PP2A by only 7%. Okadaic acid, but not tautomycin, induced the activation of both PKBalpha and PKBbeta. Finally, PP2A subunits were found in several subcellular compartments, including plasma membranes (PM) where the phosphorylation of PKB is thought to occur. In summary, our results suggest that PP2A is the principal phosphatase that dephosphorylates PKB in adipocytes.

Keywords

  • Microbiology
  • Animal
  • Phosphorylation
  • Adipocytes/cytology/drug effects/enzymology
  • Antibiotics
  • Antifungal/pharmacology
  • Cells
  • Cultured
  • Enzyme Inhibitors/pharmacology
  • Phosphoprotein Phosphatase/antagonists & inhibitors/*metabolism
  • Okadaic Acid/pharmacology
  • Rats
  • Subcellular Fractions
  • Support
  • Non-U.S. Gov't
  • Proto-Oncogene Proteins/*metabolism

Other

Published
  • Insulin Signal Transduction
  • ISSN: 1873-3913
Eva Degerman
E-mail: eva.degerman [at] med.lu.se

Professor

Insulin Signal Transduction

+46 46 222 85 83

+46 70 885 83 62

BMC C1121b

66

Lund University Diabetes Centre, CRC, SUS Malmö, Entrance 72, House 91:12. SE-205 02 Malmö. Telephone: +46 40 39 10 00