Mechanism of Protein Kinase B Activation by Insulin/Insulin-Like Growth Factor-1 Revealed by Specific Inhibitors of Phosphoinositide 3-Kinase—Significance for Diabetes and Cancer
| Autor: | Brian A. Hemmings, Roger Meier, Mirjana Andjelkovic, Jongsun Park, Ivana Galetic, Daniela Brodbeck |
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| Rok vydání: | 1999 |
| Předmět: |
AKT1
P70-S6 Kinase 1 Protein Serine-Threonine Kinases Phosphatidylinositols mTORC2 Receptor tyrosine kinase Catalytic Domain Neoplasms Proto-Oncogene Proteins Diabetes Mellitus Animals Humans Insulin Pharmacology (medical) Enzyme Inhibitors Phosphorylation Protein kinase B Phosphoinositide-3 Kinase Inhibitors Pharmacology Phosphoinositide 3-kinase biology Akt/PKB signaling pathway Chemistry Insulin-Like Growth Factor Binding Protein 1 Pleckstrin homology domain Biochemistry biology.protein Proto-Oncogene Proteins c-akt |
| Zdroj: | Pharmacology & Therapeutics. 82:409-425 |
| ISSN: | 0163-7258 |
| DOI: | 10.1016/s0163-7258(98)00071-0 |
| Popis: | Protein kinase B (PKB) is a member of the second messenger subfamily of protein kinases. The three isoforms of PKB identified have an amino-terminal pleckstrin homology domain, a central kinase domain, and a carboxy-terminal regulatory domain. PKB is the major downstream target of receptor tyrosine kinases that signal via the phosphoinositide (PI) 3-kinase. The crucial role of lipid second messengers in PKB activation has been dissected through the use of the PI 3-kinase-specific inhibitors wortmannin and LY294002. Receptor-activated PI 3-kinase synthesises the lipid second messenger PI-3,4,5-trisphosphate, leading to the recruitment of PKB to the membrane. Membrane attachment of PKB is mediated by its pleckstrin homology domain binding to PI-3,4,5-trisphosphate or PI-3,4-bisphosphate with high affinity. Activation of PKB α and β is then achieved at the plasma membrane by phosphorylation of Thr308/309 in the A-loop of the kinase domain and Ser473/474 in the carboxy-terminal regulatory region, respectively. The upstream kinase that phosphorylates PKB on Thr308, termed PI-dependent protein kinase-1, has been identified and extensively characterised. A candidate for the Ser473/474 kinase, termed the integrin-linked kinase, has been identified recently. Activated PKB is implicated in glucose metabolism, transcriptional control, and in the regulation of apoptosis in many different cell types. Stimulation of PKB activity protects cells from apoptosis by phosphorylation and inactivation of the pro-apoptotic protein BAD. These results could explain why PKB is overexpressed in some ovarian, breast, and pancreatic carcinomas. |
| Databáze: | OpenAIRE |
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