RAFT1 phosphorylation of the translational regulators p70 S6 kinase and 4E-BP1
RAFT1 phosphorylation of the translational regulators p70 S6 kinase and 4E-BP1
复制标题
DOI：
10.1073/pnas.95.4.1432
复制
发表时间：
1998-02-17
影响因子：
11.1
通讯作者：
Sabatini, DM
中科院分区：
文献类型：
--
作者：
Burnett, PE;Barrow, RK;Sabatini, DM
雷帕霉素与其细胞内受体FKBP 12的复合物与RAFT 1/FRAP/mTOR相互作用，RAFT 1/FRAP/mTOR是体内雷帕霉素敏感的靶点，也是共济失调毛细血管扩张突变（ATM）相关激酶家族的成员，与磷脂酰肌醇3-激酶的催化结构域具有同源性。目前人们对RAFT 1在雷帕霉素敏感途径中的功能及其与该途径下游组分（例如p70 S6激酶和4 E-BP 1）的联系知之甚少。在这里，我们表明RAFT 1直接磷酸化p70（S6 k）4 E-BP 1和4 E-BP 2，血清刺激RAFT 1激酶活性的动力学类似于p70（S6 k）和4 E-BP 1磷酸化，RAFT 1磷酸化Thr-389上的p70（S6 k），Thr-389是一个残基，其磷酸化是体内雷帕霉素敏感的，是S6激酶活性所必需的，Thr-36和Thr-45上的4 E-BP 1的RAFT 1磷酸化在体外阻断了其与帽结合蛋白eIF-4 E的结合，并且Thr-45的磷酸化似乎是体内4 E-BP 1-eIF-4 E相互作用的主要调节剂，RAFT 1比4 E-BP 1更有效地磷酸化p70（S6 k），两种蛋白质的磷酸化位点几乎没有同源性。这提出了一种可能性，即在体内，一种类似于p70（S6 k）的未鉴定的激酶被RAFT 1磷酸化激活，并作用于4 E-BP 1的雷帕霉素敏感磷酸化位点。
The complex of rapamycin with its intracellular receptor, FKBP12, interacts with RAFT1/FRAP/mTOR, the in vivo rapamycin-sensitive target and a member of the ataxia telangiectasia mutated (ATM)-related family of kinases that share homology with the catalytic domain of phosphatidylinositol 3-kinase. The function of RAFT1 in the rapamycin-sensitive pathway and its connection to downstream components of the pathway, such as p70 S6 kinase and 4E-BP1, are poorly understood. Here, we show that RAFT1 directly phosphorylates p70(S6k) 4E-BP1, and 4E-BP2 and that serum stimulates RAFT1 kinase activity with kinetics similar to those of p70(S6k) and 4E-BP1 phosphorylation, RAFT1 phosphorylates p70(S6k) on Thr-389, a residue whose phosphorylation is rapamycin-sensitive in vivo and necessary for S6 kinase activity, RAFT1 phosphorylation of 4E-BP1 on Thr-36 and Thr-45 blocks its association with the cap-binding protein, eIF-4E, in vitro, and phosphorylation of Thr-45 seems to he the major regulator of the 4E-BP1-eIF-4E interaction in vivo, RAFT1 phosphorylates p70(S6k) much more effectively than 4E-BP1, and the phosphorylation sites on the two proteins show little homology. This raises the possibility that, in vivo, an unidentified kinase analogous to p70(S6k) is activated by RAFT1 phosphorylation and acts at the rapamycin-sensitive phosphorylation sites of 4E-BP1.