Yean S L, Lin R J
Department of Microbiology, University of Texas, Austin 78712-1095.
Mol Cell Biol. 1991 Nov;11(11):5571-7. doi: 10.1128/mcb.11.11.5571-5577.1991.
U4 and U6 small nuclear RNAs reside in a single ribonucleoprotein particle, and both are required for pre-mRNA splicing. The U4/U6 and U5 small nuclear ribonucleoproteins join U1 and U2 on the pre-mRNA during spliceosome assembly. Binding of U4 is then destabilized prior to or concomitant with the 5' cleavage-ligation. In order to test the role of U4 RNA, we isolated a functional spliceosome by using extracts prepared from yeast cells carrying a temperature-sensitive allele of prp2 (rna2). The isolated prp2 delta spliceosome contains U2, U5, U6, and possibly also U1 and can be activated to splice the bound pre-mRNA. U4 RNA does not associate with the isolated spliceosomes and is shown not to be involved in the subsequent cleavage-ligation reactions. These results are consistent with the hypothesis that the role of U4 in pre-mRNA splicing is to deliver U6 to the spliceosome.
U4和U6小核RNA存在于单个核糖核蛋白颗粒中，二者都是前体mRNA剪接所必需的。在剪接体组装过程中，U4/U6和U5小核糖核蛋白与前体mRNA上的U1和U2结合。在5' 切割-连接之前或同时，U4的结合变得不稳定。为了测试U4 RNA的作用，我们使用从携带prp2（rna2）温度敏感等位基因的酵母细胞制备的提取物分离出了一个功能性剪接体。分离出的prp2δ剪接体含有U2、U5、U6，可能还含有U1，并且可以被激活以剪接结合的前体mRNA。U4 RNA不与分离出的剪接体结合，并且显示不参与随后的切割-连接反应。这些结果与U4在前体mRNA剪接中的作用是将U6递送至剪接体这一假设一致。
