Role of translocation in the activation and function of protein kinase B

M Andjelković, D R Alessi, R Meier, A Fernandez, N J Lamb, M Frech, P Cron, P Cohen, J M Lucocq, B A Hemmings

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910 Citations (Scopus)


We have investigated the role of subcellular localization in the regulation of protein kinase B (PKB) activation. The myristoylation/palmitylation motif from the Lck tyrosine kinase was attached to the N terminus of protein kinase B to alter its subcellular location. Myristoylated/palmitylated (m/p)-PKBalpha was associated with the plasma membrane of transfected cells, whereas the wild-type kinase was mostly cytosolic. The activity of m/p-PKBalpha was 60-fold higher compared with the unstimulated wild-type enzyme, and could not be stimulated further by growth factors or phosphatase inhibitors. In vivo 32P labeling and mutagenesis demonstrated that m/p-PKBalpha activity was due to phosphorylation on Thr308 and Ser473, that are normally induced on PKB following stimulation of the cells with insulin or insulin-like growth factor-1 (IGF-1). A dominant negative form of phosphoinositide 3-kinase (PI3-K) did not affect m/p-PKBalpha activity. The pleckstrin homology (PH) domain of m/p-PKBalpha was not required for its activation or phosphorylation on Thr308 and Ser473, suggesting that this domain may serve as a membrane-targeting module. Consistent with this view, PKBalpha was translocated to the plasma membrane within minutes after stimulation with IGF-1. This translocation required the PH domain and was sensitive to wortmannin. Our results indicate that PI3-K activity is required for translocation of PKB to the plasma membrane, where its activation occurs through phosphorylation of the same sites that are induced by insulin or IGF-1. Following activation the kinase detached from the membrane and translocated to the nucleus.
Original languageEnglish
Pages (from-to)31515-24
Number of pages10
JournalJournal of Biological Chemistry
Issue number50
Publication statusPublished - 12 Dec 1997


  • Amino Acid Substitution
  • Biological Transport
  • Cell Membrane
  • Cells, Cultured
  • Chromones
  • Enzyme Activation
  • Enzyme Inhibitors
  • Humans
  • Insulin-Like Growth Factor I
  • Morpholines
  • Phosphorylation
  • Protein Sorting Signals
  • Protein-Serine-Threonine Kinases
  • Protein-Tyrosine Kinases
  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-akt
  • Serine
  • Threonine


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