THE ROLE OF EXON SEQUENCES IN SPLICE SITE SELECTION
THE ROLE OF EXON SEQUENCES IN SPLICE SITE SELECTION
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DOI：
10.1101/gad.7.3.407
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发表时间：
1993-03-01
影响因子：
10.5
通讯作者：
SHIMURA, Y
中科院分区：
文献类型：
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作者：
WATAKABE, A;TANAKA, K;SHIMURA, Y
以小鼠免疫球蛋白MU(IgM)前-mRNA为模型底物进行体外剪接，探讨了外显子序列在剪接中的作用。我们发现，IgM基因M2外显子5‘端的缺失可以消除其直接上游内含子的剪接。当在缺失区域内发现的富嘌呤序列被重新插入到缺失构建体中时，剪接被恢复。这个M2外显子序列能够刺激包含次优3‘剪接位点序列的果蝇双性前mRNA的异源内含子的剪接。这些结果表明，IgM M2外显子序列具有剪接增强子的功能。我们发现，M2外显子序列刺激了早期剪接复合体的组装。体外竞争实验表明，这种刺激作用是通过一些反式作用因子的相互作用来实现的。我们的结果表明，U1SnRNP是一个这样的因素。我们认为，剪接机械组件对增强子外显子序列的识别在剪接位点的选择中起着至关重要的作用，不仅对IgM前-mRNA，而且对其他前-mRNAs都是如此。我们将这种序列称为外显子识别序列(ERS)。
Using mouse immunoglobulin mu (IgM) pre-mRNA as the model substrate for in vitro splicing, we have explored the role of exon sequences in splicing. We have found that deletion of the 5' portion of exon M2 of the IgM gene abolishes the splicing of its immediately upstream intron. Splicing was restored when a purine-rich sequence found within the deleted region was reinserted into the deletion construct. This M2 exon sequence was able to stimulate the splicing of a heterologous intron of the Drosophila doublesex pre-mRNA that contains a suboptimal 3' splice site sequence. These results show that the IgM M2 exon sequence functions as a splicing enhancer. We found that the assembly of the early splicing complex is stimulated by the M2 exon sequence. In vitro competition experiments show that this stimulatory effect is mediated by the interaction of some trans-acting factors. Our results suggest that the U1 snRNP is one such factor. We propose that recognition of an enhancer exon sequence by the components of splicing machinery plays a vital role in the selection of splice sites, not only for the IgM pre-mRNA but for other pre-mRNAs. We designate such a sequence as exon recognition sequence (ERS).