Shuster E O, Guthrie C
Department of Biochemistry and Biophysics, University of California, San Francisco 94143.
Cell. 1988 Oct 7;55(1):41-8. doi: 10.1016/0092-8674(88)90007-4.
Yeast U2 snRNA (1175 nucleotides) is six times larger than its mammalian counterpart (188 nucleotides). Using deletion analysis, we show that the molecule can be divided into three phenotypically distinct domains. As expected, the highly conserved 5' domain (approximately 120 nucleotides) is absolutely essential for viability. Surprisingly, however, deletion of the central 945 nucleotides has no effect on growth rate. In contrast, removal of sequences in the 3' terminal 110 nucleotides results in low numbers of slow-growing colonies; these cells contain U2 with altered 3' ends. This domain can be folded into a secondary structure that strongly resembles the 3' terminal stem-loop IV of human U2. We conclude that yeast U2 contains two functionally important elements. While the 5' domain is known to be directly involved in the splicing reaction, the 3' domain may function primarily in the generation of stable small nuclear ribonucleoprotein particles.
酵母U2小核RNA（1175个核苷酸）比其哺乳动物对应物（188个核苷酸）大六倍。通过缺失分析，我们表明该分子可分为三个表型不同的结构域。正如预期的那样，高度保守的5'结构域（约120个核苷酸）对于生存力绝对至关重要。然而，令人惊讶的是，删除中央的945个核苷酸对生长速率没有影响。相反，去除3'末端110个核苷酸中的序列会导致生长缓慢的菌落数量减少；这些细胞含有3'末端改变的U2。该结构域可折叠成一种二级结构，与人类U2的3'末端茎环IV非常相似。我们得出结论，酵母U2包含两个功能重要的元件。虽然已知5'结构域直接参与剪接反应，但3'结构域可能主要在稳定的小核核糖核蛋白颗粒的生成中发挥作用。
