Nature：内含子研究获突破

　　

生物通报道，英国MRC分子生物学实验室，哈佛大学医学院等处的研究者在最新的Nature杂志上发表新见解，解析内含子剪接方面的研究。

 

人类基因组上包含有内含子和外显子两种序列，通常外显子通过转录可以表达某种蛋白，而内含子在mRNA被翻译成蛋白之前被删除掉。剪接这些内含子的细胞器被称为：剪接体。

 

人类剪接体U1的核内小分子核糖核蛋白颗粒（snRNPs）包含有U1小分子核内小RNA和10种蛋白，snRNP能识别5’端剪接位点内部的信使RNAs前体和内含子剪接的精确位点。

 

本文的研究者用5.5A分辨率的仪器对剪接体U1进行分析，解析了该分子的晶体结构，研究结果对snRNPs的作用机制以及如何与其他亚单位相互作用的研究有重要的意义，显示了U1snRNP识别内含子的起始端，并剪接内含子的结构机制。

 

生物通推荐原文检索：Crystal structure of human spliceosomal U1 snRNP at 5.5 A  resolution

Human spliceosomal U1 small nuclear ribonucleoprotein particles (snRNPs), which consist of U1 small nuclear RNA and ten proteins, recognize the 5' splice site within precursor messenger RNAs and initiate the assembly of the spliceosome for intron excision. An electron density map of the functional core of U1 snRNP at 5.5 Å resolution has enabled us to build the RNA and, in conjunction with site-specific labelling of individual proteins, to place the seven Sm proteins, U1-C and U1-70K into the map. Here we present the detailed structure of a spliceosomal snRNP, revealing a hierarchical network of intricate interactions between subunits. A striking feature is the amino (N)-terminal polypeptide of U1-70K, which extends over a distance of 180 Å from its RNA binding domain, wraps around the core domain consisting of the seven Sm proteins and finally contacts U1-C, which is crucial for 5'-splice-site recognition. The structure of U1 snRNP provides insights into U1 snRNP assembly and suggests a possible mechanism of 5'-splice-site recognition.