Several macromolecular machines collaborate to produce eukaryotic messenger RNA. RNA polymerase II (Pol II) translocates along genes that are up to millions of base pairs in length and generates a flexible RNA copy of the DNA template. This nascent RNA harbours introns that are removed by the spliceosome, which is a megadalton ribonucleoprotein complex that positions the distant ends of the intron into its catalytic centre. Emerging evidence that the catalytic spliceosome is physically close to Pol II in vivo implies that transcription and splicing occur on similar timescales and that the transcription and splicing machineries may be spatially constrained. In this Review, we discuss aspects of spliceosome assembly, transcription elongation and other co-transcriptional events that allow the temporal coordination of co-transcriptional splicing.

中文翻译：

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剪接和转录接触碱基：共转录剪接体的组装和功能

几种大分子机器合作生产真核信使RNA。RNA聚合酶II（Pol II）沿基因移动，该基因的长度可达数百万个碱基对，并生成DNA模板的灵活RNA副本。这种新生的RNA带有被剪接体去除的内含子，该剪接体是一种megadalton核糖核蛋白复合物，可将内含子的远端定位到其催化中心。体内新证据表明催化剪接体在物理上接近Pol II这意味着转录和剪接在相似的时间尺度上发生，并且转录和剪接的机器可能在空间上受到限制。在这篇综述中，我们讨论了剪接体组装，转录延伸和其他共转录事件的方面，这些方面允许共转录剪接的时间协调。