Ltv1 is required for efficient nuclear export of the ribosomal small subunit in Saccharomyces cerevisiae
Ltv1 is required for efficient nuclear export of the ribosomal small subunit in Saccharomyces cerevisiae
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DOI：
10.1534/genetics.106.062117
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发表时间：
2006-10-01
期刊：
影响因子：
3.3
通讯作者：
Lycan, Deborah E.
中科院分区：
文献类型：
--
作者：
Seiser, Robert M.;Sundberg, Alexandra E.;Lycan, Deborah E.
在真核生物中，40S和60S核糖体亚基在细胞核中组装，并独立地输出到细胞质中。60s的核出口需要接头蛋白Nmd3，但还没有发现40s的类似接头。Ltv1是一种非必需的非核糖体蛋白，在酵母中是40s亚基生物发生所必需的。缺乏LTV1的细胞生长缓慢，对蛋白质合成抑制剂高度敏感，产生的40s亚基大约是野生型细胞的一半。Litv1与CRM1相互作用，与43S/40S亚基以蔗糖梯度共沉积，并与晚43S颗粒交配。在这里，我们证明了Ltv1以一种依赖于CRM1的方式在细胞核和细胞质之间穿梭，并且它含有一个足以指导含有NLS的报告分子输出的功能性NES。从5‘-ITS1 rRNA和40S核糖体蛋白RPS3的分布变化来判断，Delta ltw1突变体的小亚基输出减少。最后，我们展示了LTV1和YRB2之间的遗传相互作用，YRB2基因编码一个RAN-GTP-，CRM1结合蛋白，促进小亚基输出。我们认为，Ltv1是连接核输出机制和小亚基的几种可能的适配蛋白之一。
In eukaryotes, 40S and 60S ribosomal subunits are assembled in the nucleus and exported to the cytoplasm independently of one another. Nuclear export of the 60S requires the adapter protein Nmd3, but no analogous adapter has been identified for the 40S. Ltv1 is a nonessential, nonribosomal protein that is required for 40S subunit biogenesis in yeast. Cells lacking LTV1 grow slowly, are hypersensitive to inhibitors of protein synthesis, and produce about half as many 40S subunits as do wild-type cells. Ltv1 interacts with Crm1, co-sediments in sucrose gradients with 43S/40S subunits, and copurifies with late 43S particles. Here we show that Ltv1 shuttles between nucleus and cytoplasm in a Crm1-dependent manner and that it contains a functional NES that is sufficient to direct the export of an NLS-containing reporter. Small subunit export is reduced in Delta ltv1 mutants, as judged by the altered distribution of the 5'-ITS1 rRNA and the 40S ribosomal protein RpS3. Finally, we show a genetic interaction between LTV1 and YRB2, a gene that encodes a Ran-GTP-, Crm1-binding protein that facilitates the small subunit export. We propose that Ltv1 functions as one of several possible adapter proteins that link the nuclear export machinery to the small subunit.