Exp5 exports eEF1A via tRNA from nuclei and synergizes with other transport pathways to confine translation to the cytoplasm
Exp5 exports eEF1A via tRNA from nuclei and synergizes with other transport pathways to confine translation to the cytoplasm
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DOI：
10.1093/emboj/cdf613
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发表时间：
2002-11-15
期刊：
影响因子：
11.4
通讯作者：
Görlich, D
中科院分区：
文献类型：
--
作者：
Bohnsack, MT;Regener, K;Görlich, D
输入蛋白- β型转运受体介导了细胞核和细胞质之间的绝大多数转运途径。我们在这里确定翻译延伸因子1A （eEF1A）是RanBP21/出口蛋白5 （Exp5）的主要核输出底物。这种货物-输出蛋白相互作用相当不寻常，因为eEF1A不是直接结合输出蛋白，而是通过氨基酰化的trna结合。因此，Exp5代表了第二个直接结合rna的输出蛋白，并与export -t并行介导tRNA的输出。最近有人提出，10-15%的细胞翻译发生在细胞核内。我们的数据排除了这种情况，而是表明核转译受到核出口机制的积极抑制。我们发现绝大多数翻译起始因子（eIF2, eIF2B, eIF3, eIF4A1， eIF5和eIF5B），所有三个延伸因子（eEF1A， eEF1B和eEF2）和终止因子eRF1都严格排除在细胞核之外。除了Exp5和进口蛋白13外，CRM1和尚未确定的出口蛋白也有助于细胞核翻译因子的耗竭。
Importin beta-type transport receptors mediate the vast majority of transport pathways between cell nucleus and cytoplasm. We identify here the translation elongation factor 1A (eEF1A) as the predominant nuclear export substrate of RanBP21/exportin 5 (Exp5). This cargo-exportin interaction is rather unusual in that eEF1A binds the exportin not directly, but instead via aminoacylated tRNAs. Exp5 thus represents the second directly RNA-binding exportin and mediates tRNA export in parallel with exportin-t. It was suggested recently that 10-15% of the cellular translation would occur in the nucleus. Our data rule out such a scenario and instead suggest that nuclear translation is actively suppressed by the nuclear export machinery. We found that the vast majority of translation initiation factors (eIF2, eIF2B, eIF3, eIF4A1, eIF5 and eIF5B), all three elongation factors (eEF1A, eEF1B and eEF2) and the termination factor eRF1 are strictly excluded from nuclei. Besides Exp5 and importin 13, CRM1 and as yet unidentified exportins also contribute to the depletion of translation factors from nuclei.