A large nucleolar U3 ribonucleoprotein required for 18S ribosomal RNA biogenesis
A large nucleolar U3 ribonucleoprotein required for 18S ribosomal RNA biogenesis
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DOI：
10.1038/nature00769
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发表时间：
2002-06-27
期刊：
影响因子：
64.8
通讯作者：
Baserga, SJ
中科院分区：
文献类型：
--
作者：
Dragon, F;Gallagher, JEG;Baserga, SJ
U3小核RNA （small nucleolar RNA, snoRNA）是盒C/D类snoRNA的一员，虽然在30多年前就与剪接体小核RNA （snrna）一起被鉴定出来（1,2），但其功能及其相关的蛋白组分仍然不太清楚。U3 snoRNA在真核生物中普遍存在，在所有已测试过U3 snoRNA的生物中，U3 snoRNA是18s前核糖体RNA的核核加工所必需的（3,4）。生化和遗传学分析表明，u3 -pre- rrnabase配对相互作用介导核内溶前rrna裂解(3)。在这里，我们从酿酒酵母中纯化了一个含有U3 snoRNA和28个蛋白的大核糖核蛋白（RNP）复合物。17个新蛋白（Utp1-17）和Rrp5，以及10个已知成分。Utp蛋白是核仁蛋白，与U3 snoRNA特异性相关。Utp蛋白的缺失阻碍了18S rRNA的产生，这表明它们是活跃的前rRNA加工复合体的一部分。基于其大的尺寸（80S；计算的相对分子质量至少为2,200,000）和功能，该复合物可能对应于新生的pre-rRNAs的5'端末端的末端旋钮。我们把这个大RNP称为小亚基（SSU）过程。
Although the U3 small nucleolar RNA (snoRNA), a member of the box C/D class of snoRNAs, was identified with the spliceosomal small nuclear RNAs (snRNAs) over 30 years ago(1,2), its function and its associated protein components have remained more elusive. The U3 snoRNA is ubiquitous in eukaryotes and is required for nucleolar processing of pre-18S ribosomal RNA in all organisms where it has been tested(3,4). Biochemical and genetic analyses suggest that U3-pre-rRNAbase-pairing interactions mediate endonucleolytic pre-rRNA cleavages(3). Here we have purified a large ribonucleoprotein (RNP) complex from Saccharomyces cerevisiae that contains the U3 snoRNA and 28 proteins. Seventeen new proteins (Utp1-17) and Rrp5 were present, as were ten known components. The Utp proteins are nucleolar and specifically associated with the U3 snoRNA. Depletion of the Utp proteins impedes production of the 18S rRNA, indicating that they are part of the active pre-rRNA processing complex. On the basis of its large size (80S; calculated relative molecular mass of at least 2,200,000) and function, this complex may correspond to the terminal knobs present at the 5' ends of nascent pre-rRNAs. We have termed this large RNP the small subunit (SSU) processome.