Chanfreau G, Noble S M, Guthrie C
Department of Biochemistry and Biophysics, UCSF School of Medicine, San Francisco, CA 94143-0448.
Science. 1996 Nov 29;274(5292):1511-4. doi: 10.1126/science.274.5292.1511.
The 3' ends of most eukaryotic messenger RNAs are generated by internal cleavage and polyadenylation. In mammals, there is a strict dependence of both reactions on the sequence AAUAAA, which occurs upstream of polyadenylation [poly(A)] sites and which is recognized by CPSF. In contrast, cis-acting signals for yeast 3'-end generation are highly divergent from those of mammals, suggesting that trans-acting factors other than poly(A) polymerase would not be conserved. The essential yeast protein Brr5/Ysh1 shows sequence similarity to subunits of mammalian CPSF and is required for 3'-end processing in vivo and in vitro. These results demonstrate a structural and functional conservation of the yeast and mammalian 3'-end processing machineries despite a lack of conservation of the cis sequences.
大多数真核生物信使核糖核酸（mRNA）的3'末端是通过内部切割和多聚腺苷酸化产生的。在哺乳动物中，这两个反应都严格依赖于序列AAUAAA，该序列出现在多聚腺苷酸化[poly(A)]位点的上游，并被CPSF识别。相比之下，酵母3'末端生成的顺式作用信号与哺乳动物的信号高度不同，这表明除了多聚(A)聚合酶之外的反式作用因子不会保守。酵母必需蛋白Brr5/Ysh1与哺乳动物CPSF的亚基具有序列相似性，并且在体内和体外的3'末端加工中都是必需的。这些结果表明，尽管顺式序列缺乏保守性，但酵母和哺乳动物的3'末端加工机制在结构和功能上具有保守性。
