The putative GTPases Nog1p and Lsg1p are required for 60S ribosomal subunit biogenesis and are localized to the nucleus and cytoplasm, respectively
The putative GTPases Nog1p and Lsg1p are required for 60S ribosomal subunit biogenesis and are localized to the nucleus and cytoplasm, respectively
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DOI：
10.1128/mcb.23.12.4344-4355.2003
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发表时间：
2003-06-01
影响因子：
5.3
通讯作者：
Johnson, A
中科院分区：
文献类型：
--
作者：
Kallstrom, G;Hedges, J;Johnson, A
我们鉴定了两个重要的GTP酶，Nog1p和Lsg1p，它们与用核出口适配器Nmd3p纯化的60S核糖体亚基亲和力相关。Nog1p和Lsg1p分别是核仁和细胞质，并不同时位于同一颗粒上，反映了Nmd3p穿梭在核内和核外的路径。NOG1和LSG1的条件突变体在60S亚基的生物发生过程中都存在缺陷，并且在限制性温度下表现出60S亚基水平的降低。这两个基因的突变体还在核仁中积累了60S核糖体报告Rp125-EGFP，这表明这两种蛋白都是从核仁输出亚基所必需的。由于Lsg1p是细胞质的，它在核出口中的作用可能是间接的。我们认为，Lsg1p是从与新生的60S亚基相关的核穿梭而来的输出因子(S)循环所必需的。
We characterized two essential putative GTPases, Nog1p and Lsg1p, that are found associated with free 60S ribosomal subunits affinity purified with the nuclear export adapter Nmd3p. Nog1p and Lsg1p are nucleolar and cytoplasmic, respectively, and are not simultaneously on the same particle, reflecting the path of Nmd3p shuttling in and out of the nucleus. Conditional mutants of both NOG1 and LSG1 are defective in 60S subunit biogenesis and display diminished levels of 60S subunits at restrictive temperature. Mutants of both genes also accumulate the 60S ribosomal reporter Rp125-eGFP in the nucleolus, suggesting that both proteins are needed for subunit export from the nucleolus. Since Lsg1p is cytoplasmic, its role in nuclear export is likely to be indirect. We suggest that Lsg1p is needed to recycle an export factor(s) that shuttles from the nucleus associated with the nascent 60S subunit.