Characterization of the Initiation Factor eIF2B and Its Regulation in Drosophila melanogaster * 210
Characterization of the Initiation Factor eIF2B and Its Regulation in Drosophila melanogaster * 210
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DOI：
10.1074/jbc.m008041200
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发表时间：
2001-02
期刊：
影响因子：
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通讯作者：
Daniel D. Williams;G. Pavitt;C. Proud
中科院分区：
文献类型：
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作者：
Daniel D. Williams;G. Pavitt;C. Proud
真核起始因子（eIF）2B催化mRNA翻译起始中的关键调节步骤。eIF 2B在哺乳动物和酵母中得到了很好的表征，尽管在其他真核生物中对其知之甚少。eIF 2B是介导eIF 2上GDP交换为GTP的杂五聚体。在哺乳动物和酵母中，其活性受eIF 2 α磷酸化的调节。在这里，我们克隆了果蝇cDNA编码的多肽，显示出与酵母和哺乳动物的eIF 2B亚基的实质相似性。它们还表现出这些蛋白质的其他保守特征。D.黑腹果蝇eIF 2B α赋予酵母中eIF 2B功能的调节，而eIF 2B ε显示鸟嘌呤核苷酸交换活性。与哺乳动物eIF 2B ε相同，D.黑腹果蝇eIF 2B ε被糖原合成酶激酶-3和酪蛋白激酶II磷酸化。部分纯化的D.黑腹果蝇eIF 2B通过糖原合成酶激酶-3抑制其活性。D.黑腹果蝇S2 Schneider细胞显示eIF 2B活性，其被eIF 2 α的磷酸化抑制，表明昆虫因子的调节类似于来自其他物种的eIF 2B。在S2细胞中，血清饥饿增加eIF 2 α磷酸化，这与抑制eIF 2B相关，血清处理可逆转这两种作用。这表明eIF 2 α磷酸化和eIF 2B活性受到血清的动态调节。S2细胞中eIF 2 α磷酸化也因内质网应激而增加。这是从D.黑腹菌
Eukaryotic initiation factor (eIF) 2B catalyzes a key regulatory step in the initiation of mRNA translation. eIF2B is well characterized in mammals and in yeast, although little is known about it in other eukaryotes. eIF2B is a hetropentamer which mediates the exchange of GDP for GTP on eIF2. In mammals and yeast, its activity is regulated by phosphorylation of eIF2α. Here we have clonedDrosophila melanogaster cDNAs encoding polypeptides showing substantial similarity to eIF2B subunits from yeast and mammals. They also exhibit the other conserved features of these proteins. D. melanogaster eIF2Bα confers regulation of eIF2B function in yeast, while eIF2Bε shows guanine nucleotide exchange activity. In common with mammalian eIF2Bε, D. melanogaster eIF2Bε is phosphorylated by glycogen synthase kinase-3 and casein kinase II. Phosphorylation of partially purifiedD. melanogaster eIF2B by glycogen synthase kinase-3 inhibits its activity. Extracts of D. melanogaster S2 Schneider cells display eIF2B activity, which is inhibited by phosphorylation of eIF2α, showing the insect factor is regulated similarly to eIF2B from other species. In S2 cells, serum starvation increases eIF2α phosphorylation, which correlates with inhibition of eIF2B, and both effects are reversed by serum treatment. This shows that eIF2α phosphorylation and eIF2B activity are under dynamic regulation by serum. eIF2α phosphorylation is also increased by endoplasmic reticulum stress in S2 cells. These are the first data concerning the structure, function or control of eIF2B from D. melanogaster.