Terns M P, Lund E, Dahlberg J E
Department of Biomolecular Chemistry, University of Wisconsin, Madison 53706.
Nucleic Acids Res. 1993 Sep 25;21(19):4569-73. doi: 10.1093/nar/21.19.4569.
We demonstrate that precursors of U1 snRNA are associated with nuclear proteins prior to export to the cytoplasm. The approximately 15S complexes containing pre-U1 RNA, which we call pre-export U1 snRNPs, were identified in extracts of Xenopus laevis oocyte nuclei that were synthesizing U1 RNAs from injected U1 genes. The U1 snRNP-specific A protein was associated with nuclear pre-U1 RNA since both this protein and the RNA were co-precipitated by antibodies directed against either the m7G-cap of the precursor RNA or the U1-A protein. The interaction of the U1-A protein with pre-U1 RNA required sequences in the loop II region although this region of U1 RNA was not necessary for the association of U1 A protein with mature U1 snRNPs. The U1 A protein helps protect pre-U1 RNA against degradation in the nucleus.
我们证明，U1 snRNA的前体在输出到细胞质之前与核蛋白相关联。在非洲爪蟾卵母细胞核提取物中鉴定出了含有前体U1 RNA的约15S复合物，我们将其称为输出前U1 snRNP，这些提取物是从注射了U1基因并正在合成U1 RNA的细胞中获取的。U1 snRNP特异性A蛋白与核内前体U1 RNA相关联，因为针对前体RNA的m7G帽或U1-A蛋白的抗体可共沉淀该蛋白和RNA。U1-A蛋白与前体U1 RNA的相互作用需要环II区域中的序列，尽管U1 RNA的该区域对于U1 A蛋白与成熟U1 snRNP的关联并非必需。U1 A蛋白有助于保护前体U1 RNA在细胞核中不被降解。
