Target of rapamycin (TOR)-signaling and RAIP motifs play distinct roles in the mammalian TOR-dependent phosphorylation of initiation factor 4E-binding protein 1
Target of rapamycin (TOR)-signaling and RAIP motifs play distinct roles in the mammalian TOR-dependent phosphorylation of initiation factor 4E-binding protein 1
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DOI：
10.1074/jbc.m308573200
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发表时间：
2003-10-17
影响因子：
4.8
通讯作者：
Proud, CG
中科院分区：
文献类型：
--
作者：
Beugnet, A;Wang, XM;Proud, CG
翻译阻遏蛋白eIF 4 E结合蛋白1（4 E-BP 1，也称为PHAS-I）通过雷帕霉素敏感性mTOR（雷帕霉素的哺乳动物靶蛋白）途径磷酸化调节。最近的研究已经确定了4 E-BP 1中的两个调节基序，即4 E-BP 1的C末端的mTOR信号传导（TOS）基序和N末端的RAIP基序（以其序列命名）。最近的其他研究表明，蛋白raptor与mTOR和4 E-BP 1结合。我们发现，猛禽结合全长4 E-BP 1或C-末端片段含有TOS基序，但不包含RAIP基序的N-末端片段。TOS基序内的几个残基的突变消除了与猛禽的结合，表明TOS基序是这种相互作用所必需的。4 E-BP 1在完整细胞中的多个位点发生磷酸化。RAIP和TOS基序的去除或突变的效果不同。RAIP基序是4 E-BP 1的N和C末端位点磷酸化所必需的，而TOS基序主要影响Ser-64/65、Thr-69/70以及雷帕霉素不敏感位点Ser-101的磷酸化。依赖于RAIP基序的N-末端位点的磷酸化对雷帕霉素敏感。因此，RAIP基序促进4 E-BP 1中多个位点的mTOR依赖性磷酸化，而不依赖于4 E-BP 1/raptor相互作用。
The translational repressor protein eIF4E-binding protein 1 (4E-BP1, also termed PHAS-I) is regulated by phosphorylation through the rapamycin-sensitive mTOR ( mammalian target of rapamycin) pathway. Recent studies have identified two regulatory motifs in 4E-BP1, an mTOR-signaling (TOS) motif in the C terminus of 4E-BP1 and an RAIP motif ( named after its sequence) in the N terminus. Other recent work has shown that the protein raptor binds to mTOR and 4E-BP1. We show that raptor binds to full-length 4E-BP1 or a C-terminal fragment containing the TOS motif but not to an N-terminal fragment containing the RAIP motif. Mutation of several residues within the TOS motif abrogates binding to raptor, indicating that the TOS motif is required for this interaction. 4E-BP1 undergoes phosphorylation at multiple sites in intact cells. The effects of removal or mutation of the RAIP and TOS motifs differ. The RAIP motif is absolutely required for phosphorylation of sites in the N and C termini of 4E-BP1, whereas the TOS motif primarily affects phosphorylation of Ser-64/65, Thr-69/70, and also the rapamycin-insensitive site Ser-101. Phosphorylation of N-terminal sites that are dependent upon the RAIP motif is sensitive to rapamycin. The RAIP motif thus promotes the mTOR-dependent phosphorylation of multiple sites in 4E-BP1 independently of the 4E-BP1/raptor interaction.