• Media type: E-Article
  • Title: Dual Role of Phosphatidylinositol-3,4,5-trisphosphate in the Activation of Protein Kinase B
  • Contributor: Stokoe, David; Stephens, Leonard R.; Copeland, Terry; Gaffney, Piers R. J.; Reese, Colin B.; Painter, Gavin F.; Holmes, Andrew B.; McCormick, Frank; Hawkins, Phillip T.
  • Published: American Association for the Advancement of Science (AAAS), 1997
  • Published in: Science, 277 (1997) 5325, Seite 567-570
  • Language: English
  • DOI: 10.1126/science.277.5325.567
  • ISSN: 0036-8075; 1095-9203
  • Origination:
  • Footnote:
  • Description: <jats:p> Protein kinase B (PKB) is a proto-oncogene that is activated in signaling pathways initiated by phosphoinositide 3-kinase. Chromatographic separation of brain cytosol revealed a kinase activity that phosphorylated and activated PKB only in the presence of phosphatidylinositol-3,4,5-trisphosphate [PtdIns(3,4,5)P <jats:sub>3</jats:sub> ]. Phosphorylation occurred exclusively on threonine-308, a residue implicated in activation of PKB in vivo. PtdIns(3,4,5)P <jats:sub>3</jats:sub> was determined to have a dual role: Its binding to the pleckstrin homology domain of PKB was required to allow phosphorylation by the upstream kinase and it directly activated the upstream kinase. </jats:p>