Characterization of a 3-phosphoinositide-dependent protein kinase which phosphorylates and activates protein kinase B alpha
Characterization of a 3-phosphoinositide-dependent protein kinase which phosphorylates and activates protein kinase B alpha
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DOI：
10.1016/s0960-9822(06)00122-9
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发表时间：
1997-04-01
期刊：
影响因子：
9.2
通讯作者：
Cohen, P
中科院分区：
文献类型：
--
作者：
Alessi, DR;James, SR;Cohen, P
背景资料：蛋白激酶B（PKB），也称为c-Akt，当哺乳动物细胞被胰岛素和生长因子刺激时被迅速激活，并且目前对这种酶的兴趣大部分源于观察到它位于胞内信号传导途径上的磷酸肌醇9-激酶的“下游”。我们最近表明胰岛素或胰岛素样生长因子1诱导PKB在两个残基处的磷酸化，Thr 308和Ser 473。这两个残基的磷酸化是PKB最大活化所必需的。然而，磷酸化PKB的激酶是未知的。我们已经从兔骨骼肌提取物中纯化了50万倍的蛋白激酶，该蛋白激酶在Thr 308磷酸化PKB α并使其活性增加30倍以上。我们在几种肌醇磷脂存在下测试了该激酶，发现只有低微摩尔浓度的磷脂酰肌醇3，4，5-三磷酸（Ptdlns（3，4，5）P-3）或Ptdlns（3，4）P-2有效地激活激酶，其被命名为Ptdlns（3，4，5）P-2依赖性蛋白激酶-1（PDK 1）。在所用条件下，测试的肌醇磷脂均未激活或抑制PKB α或诱导其磷酸化。PDK 1的活性不受渥曼青霉素的影响，这表明它不太可能是磷酸肌醇3-激酶家族的成员。PDK 1可能是介导胰岛素和生长因子激活PKB的蛋白激酶之一，因此，PDK 1可能在介导第二信使Ptdlns（3，4，5）P-3和/或Ptdlns（3，4）P-2。(C)当前生物有限公司
Background: Protein kinase B (PKB), also known as c-Akt, is activated rapidly when mammalian cells are stimulated with insulin and growth factors, and much of the current interest in this enzyme stems from the observation that it lies 'downstream' of phosphoinositide 9-kinase on intracellular signalling pathways, We recently showed that insulin or insulin-like growth factor 1 induce the phosphorylation of PKB at two residues, Thr308 and Ser473. The phosphorylation of both residues is required for maximal activation of PKB. The kinases that phosphorylate PKB are, however, unknown.Results: We have purified 500 000-fold from rabbit skeletal muscle extracts a protein kinase which phosphorylates PKB alpha at Thr308 and increases its activity over 30-fold, We tested the kinase in the presence of several inositol phospholipids and found that only low micromolar concentrations of the D enantiomers of either phosphatidylinositol 3,4,5-trisphosphate (Ptdlns(3,4,5)P-3) or Ptdlns(3,4)P-2 were effective in potently activating the kinase, which has been named Ptdlns(3,4,5)P-2-dependent protein kinase-1 (PDK1). None of the inositol phospholipids tested activated or inhibited PKB alpha or induced its phosphorylation under the conditions used. PDK1 activity was not affected by wortmannin, indicating that it is not likely to be a member of the phosphoinositide 3-kinase family.Conclusions: PDK1 is likely to be one of the protein kinases that mediate the activation of PKB by insulin and growth factors, PDK1 may, therefore, play a key role in mediating many of the actions of the second messenger(s) Ptdlns(3,4,5)P-3 and/or Ptdlns(3,4)P-2. (C) Current Biology Ltd.