Mowry K L, Steitz J A
Howard Hughes Medical Institute, Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06510.
Science. 1987 Dec 18;238(4834):1682-7. doi: 10.1126/science.2825355.
In eukaryotic cells, the conversion of gene transcripts into messenger RNA's involves multiple factors, including the highly abundant small nuclear ribonucleoprotein (snRNP) complexes that mediate the splicing reaction. Separable factors are also required for the 3' end processing of histone pre-mRNA's. The two conserved signals flanking the 3' cleavage site are recognized by discrete components present in active HeLa cell extracts: the upstream stem loop associates with a nuclease-insensitive factor, while binding to the downstream element is mediated by a component having the properties of a snRNP. The sequence of the RNA moiety of the low abundance human U7 snRNP suggests how the relatively degenerate downstream element of mammalian pre-mRNA's could be recognized by RNA base-pairing.
在真核细胞中，基因转录本转化为信使核糖核酸涉及多种因素，包括介导剪接反应的高度丰富的小核核糖核蛋白（snRNP）复合体。组蛋白前体信使核糖核酸的3'端加工也需要可分离的因子。位于3'切割位点两侧的两个保守信号由活跃的HeLa细胞提取物中存在的离散成分识别：上游茎环与一种核酸酶不敏感因子结合，而与下游元件的结合则由具有snRNP特性的成分介导。低丰度人类U7 snRNP的RNA部分序列表明，哺乳动物前体信使核糖核酸相对简并的下游元件如何通过RNA碱基配对被识别。
