cell20121109-8

来自美国马萨诸塞州医学院霍华德·休斯医学研究所的Melissa J. Moore实验室发现内生的EJCs和SR蛋白协作保护mRNA的包装和压实,这篇文章刊登在最新一期《CELL》杂志上。

-2012年11月9日《细胞》


中文翻译


【题目】胞内EJC相互作用展现高序的mRNP结构和一个EJC-SR蛋白融合膜

【译文】除了移除内含子来描述真核生物转录物外,pre-mRNA剪接严重影响新生成的mRNP的蛋白组成。外显子拼接复合物(EJC)位于剪接后外显子-外显子连接点的上游,它是剪接后的mRNPs的主要成分。我们对内源性人类EJC蛋白和RNA相互作用进行了综合性分析。我们证明了在体内主要的“经典” EJC占有位点位于外显子连接点上游24nt处,并且大部分外显子连接点带有EJC。但意想不到的是,我们发现内源性EJCs能与其他的EJCs组装在一起并与其他SR蛋白形成兆道尔顿大小的复合物,这种复合物中SR蛋白对于EJC核心因子是过量的。这种紧密的关联也可以解释之前发现的EJCs和SR蛋白间的功能相似性。进一步来说,这些因子保护长链mRNA免受核酸酶的消化表明:内生的EJCs和SR蛋白协作保护mRNA的包装和压实。

英文原稿


[Title]The Cellular EJC Interactome Reveals Higher-Order mRNP Structure and an EJC-SR Protein Nexus

[Authors]Guramrit Singh, Alper Kucukural, Can Cenik, John D. Leszyk, Scott A. Shaffer, Zhiping Weng, Melissa J. Moore

[Abstract]In addition to sculpting eukaryotic transcripts by removing introns, pre-mRNA splicing greatly impacts protein composition of the emerging mRNP. The exon junction complex (EJC), deposited upstream of exon-exon junctions after splicing, is a major constituent of spliced mRNPs. Here, we report comprehensive analysis of the endogenous human EJC protein and RNA interactomes. We confirm that the major “canonical” EJC occupancy site in vivo lies 24 nucleotides upstream of exon junctions and that the majority of exon junctions carry an EJC. Unexpectedly, we find that endogenous EJCs multimerize with one another and with numerous SR proteins to form megadalton sized complexes in which SR proteins are super-stoichiometric to EJC core factors. This tight physical association may explain known functional parallels between EJCs and SR proteins. Further, their protection of long mRNA stretches from nuclease digestion suggests that endogenous EJCs and SR proteins cooperate to promote mRNA packaging and compaction.

原文地址

http://www.cell.com/abstract/S0092-8674(12)01220-2

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