Moy Terence I, Silver Pamela A
Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA.
J Cell Sci. 2002 Jul 15;115(Pt 14):2985-95. doi: 10.1242/jcs.115.14.2985.
Eukaryotic ribosome biogenesis requires multiple steps of nuclear transport because ribosomes are assembled in the nucleus while protein synthesis occurs in the cytoplasm. Using an in situ RNA localization assay in the yeast Saccharomyces cerevisiae, we determined that efficient nuclear export of the small ribosomal subunit requires Yrb2, a factor involved in Crm1-mediated export. Furthermore, in cells lacking YRB2, the stability and abundance of the small ribosomal subunit is decreased in comparison with the large ribosomal subunit. To identify additional factors affecting small subunit export, we performed a large-scale screen of temperature-sensitive mutants. We isolated new alleles of several nucleoporins and Ran-GTPase regulators. Together with further analysis of existing mutants, we show that nucleoporins previously shown to be defective in ribosomal assembly are also defective in export of the small ribosomal subunit.
真核生物核糖体的生物合成需要多个核运输步骤，因为核糖体在细胞核中组装，而蛋白质合成发生在细胞质中。通过在酿酒酵母中进行原位RNA定位分析，我们确定小核糖体亚基的有效核输出需要Yrb2，这是一种参与Crm1介导的输出的因子。此外，在缺乏YRB2的细胞中，与大核糖体亚基相比，小核糖体亚基的稳定性和丰度降低。为了鉴定影响小亚基输出的其他因子，我们对温度敏感突变体进行了大规模筛选。我们分离出了几种核孔蛋白和Ran-GTPase调节因子的新等位基因。结合对现有突变体的进一步分析，我们表明先前显示在核糖体组装中有缺陷的核孔蛋白在小核糖体亚基的输出中也有缺陷。
