Journal: The Journal of Biological Chemistry
Article Title: Akt activation by Ca 2+ /calmodulin-dependent protein kinase kinase 2 (CaMKK2) in ovarian cancer cells
doi: 10.1074/jbc.M117.778464
Figure Lengend Snippet: CaMKK2 activates Akt by direct phosphorylation at Thr-308 in a Ca2+/CaM-dependent fashion. CaMKK2, but not Akt, binds to Ca2+/CaM. A, CaMKK2 activated WT Akt, but not T308A/S473A (DM) Akt. Akt activation required the presence of Ca2+/CaM. Recombinant CaMKK2 and WT Akt or DM Akt were pre-incubated under phosphorylating conditions in the presence or absence of Ca2+/CaM. Akt peptide kinase activity was then assayed, and results were plotted as a function of CaMKK2 concentration. Values represent mean ± S.D. relative to 0 μm CaMKK2. *, p < 0.05; **, p < 0.01; ***, p < 0.001 for WT Akt ± Ca2+/CaM relative to DM Akt + Ca2+/CaM. +, p < 0.05; ++, p < 0.01 for WT Akt + Ca2+/CaM relative to WT Akt − Ca2+/CaM. n = 4 independent experiments. B, CaMKK2 phosphorylated Akt at Thr-308 but not at Ser-473. CaMKK2 and/or WT Akt or DM Akt were incubated under phosphorylating conditions in the presence of Ca2+/CaM. Akt phosphorylation at Thr-308 and Ser-473 was assessed. C, CaMKK2, but not Akt, bound Ca2+/CaM. The indicated amounts of recombinant GST-CaMKK2 and WT His-Akt were electrophoretically transferred onto PVDF membranes and incubated with biotinylated-CaM in the presence (Ca2+) or absence (EGTA) of Ca2+, and the membranes were immunoblotted for CaM.
Article Snippet: In vitro Akt peptide kinase activity assay His-tagged human full-length (WT) and DM, T308A/S473A, Akt1 recombinant proteins were pre-incubated with recombinant, baculovirus-expressed GST-tagged human full-length CaMKK2 (Life Technologies, Inc.) for 40 min at 30 °C in a pre-incubation buffer consisting of 50 m m Tris, pH 7.6, 0.5 m m DTT, 10 m m MgCl 2 , 200 μ m ATP, 0.5 mg/ml BSA, (± 1 m m CaCl 2 , 1 μ m CaM).
Techniques: Activation Assay, Recombinant, Incubation, Activity Assay, Concentration Assay