不同种类RNA的核输出由特定因子介导。
Nuclear export of different classes of RNA is mediated by specific factors.
作者信息
Jarmolowski A, Boelens W C, Izaurralde E, Mattaj I W
机构信息
European Molecular Biology Laboratory, Heidelberg, Germany.
出版信息
J Cell Biol. 1994 Mar;124(5):627-35. doi: 10.1083/jcb.124.5.627.
Various classes of RNA are exported from the nucleus to the cytoplasm, including transcripts of RNA polymerase I (large ribosomal RNAs), II (U-rich small nuclear RNAs [U snRNAs], mRNAs), and III (tRNAs, 5S RNA). Here, evidence is presented that some steps in the export of various classes of nuclear RNA are mediated by specific rather than common factors. Using microinjection into Xenopus oocytes, it is shown that a tRNA, a U snRNA, and an mRNA competitively inhibit their own export at concentrations at which they have no effect on the export of heterologous RNAs. While the export of both U snRNAs and mRNAs is enhanced by their 7-methyl guanosine cap structures, factors recognizing this structure are found to be limiting in concentration only in the case of U snRNAs. In addition to the specific factors, evidence for steps in the export process that may be common to at least some classes of RNA are provided by experiments in which synthetic homopolymeric RNAs are used as inhibitors.
各类RNA从细胞核输出到细胞质，包括RNA聚合酶I的转录本（大核糖体RNA）、II的转录本（富含尿嘧啶的小核RNA [U snRNA]、mRNA）和III的转录本（tRNA、5S RNA）。本文提供的证据表明，各类核RNA输出过程中的某些步骤是由特定而非共同的因子介导的。通过向非洲爪蟾卵母细胞显微注射发现，一种tRNA、一种U snRNA和一种mRNA在对异源RNA输出无影响的浓度下，竞争性抑制自身的输出。虽然U snRNA和mRNA的输出都因其7-甲基鸟苷帽结构而增强，但发现仅在U snRNA的情况下，识别该结构的因子浓度有限。除了特定因子外，使用合成同聚RNA作为抑制剂的实验提供了证据，表明至少某些类别的RNA在输出过程中可能存在共同步骤。
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