Ser-64 and Ser-111 in PHAS-I are dispensable for insulin-stimulated dissociation from eIF4E
Ser-64 and Ser-111 in PHAS-I are dispensable for insulin-stimulated dissociation from eIF4E
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DOI：
10.1074/jbc.m307949200
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发表时间：
2003-11-28
影响因子：
4.8
通讯作者：
Lawrence, JC
中科院分区：
文献类型：
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作者：
Ferguson, G;Mothe-Satney, I;Lawrence, JC
胰岛素刺激eIF4E结合蛋白PHAS-I中多个位点的磷酸化，导致PHAS-I.eIF4E复合体的解离，增加帽子依赖的翻译。Ser-和Ser-111位点被认为在控制PHAs-I和eIF4E的结合中起着关键作用。为了确定胰岛素的作用是否需要这些位点，我们评估了具有ALA-或ALA-111突变的PHAS-I蛋白的对照。结果表明，胰岛素不需要这两个位点的磷酸化来促进从eIF4E释放PHAS-I。此外，Ser-111的突变并不影响Thr-36/45、Ser-或Thr-69的磷酸化，Ser-111被认为是PHAS-I中其他位点磷酸化的必要启动位点。胰岛素促进缺乏Ser-111位点的PHAs-II亚型释放eIF4E，但对与第三种亚型PHAs-III结合的eIF4E的量无影响。结果表明，与广泛接受的模型相反，在细胞内控制PHAs-I与eIF4E的结合并不需要Ser-和Ser-111，这意味着在Phas-I的解离过程中Thr位点的磷酸化。EIF4E复合体。研究结果还表明，PHAS-II，而不是PHAS-III，有助于胰岛素对蛋白质合成的控制。
Insulin stimulates phosphorylation of multiple sites in the eIF4E-binding protein, PHAS-I, leading to dissociation of the PHAS-I.eIF4E complex and to an increase in cap-dependent translation. The Ser-64 and Ser-111 sites have been proposed to have key roles in controlling the association of PHAS-I and eIF4E. To determine whether the effects of insulin require these sites, we assessed the control of PHAS-I proteins having Ala-64 or Ala-111 mutations. The results indicate that phosphorylation of neither site is required for insulin to promote release of PHAS-I from eIF4E. Also, the mutation of Ser-111, which has been proposed to serve as a necessary priming site for the phosphorylation of other sites in PHAS- I, did not affect the phosphorylation of Thr-36/45, Ser-64, or Thr-69. Insulin promoted the release of eIF4E from PHAS-II, a PHAS isoform that lacks the Ser-111 site, but it was without effect on the amount of eIF4E bound to the third isoform, PHAS-III. The results demonstrate that contrary to widely accepted models, Ser-64 and Ser-111 are not required for the control of PHAS- I binding to eIF4E in cells, implicating phosphorylation of the Thr sites in dissociation of the PHAS- I . eIF4E complex. The findings also indicate that PHAS-II, but not PHAS-III, contributes to the control of protein synthesis by insulin.