Fu X D, Maniatis T
Department of Biochemistry and Molecular Biology, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 1992 Mar 1;89(5):1725-9. doi: 10.1073/pnas.89.5.1725.
The splicing factor SC35 is required for the first step of the splicing reaction and for the assembly of the earliest ATP-dependent complex detected by native gel electrophoresis (A complex). Here we investigate the role of SC35 in mediating specific interactions between U1 and U2 small nuclear ribonucleoprotein particles (snRNPs) and the 5' and 3' splice sites of pre-mRNA. We show that U1 snRNP interacts specifically with both the 5' and 3' splice sites in the presence of ATP and that SC35 is required for these ATP-dependent interactions. Significantly, the SC35-dependent interaction between U1 snRNP and the 3' splice site requires U2 snRNP but not the 5' splice site. We also show that SC35 is required for the ATP-dependent interaction between U2 snRNP and the branch-point sequence. We conclude that SC35 may play an important role in mediating specific interactions between splicing components bound to the 5' and 3' splice sites.
剪接因子SC35是剪接反应第一步以及天然凝胶电泳检测到的最早的ATP依赖性复合物（A复合物）组装所必需的。在此，我们研究了SC35在介导U1和U2小核核糖核蛋白颗粒（snRNP）与前体mRNA的5'和3'剪接位点之间特异性相互作用中的作用。我们发现，在ATP存在的情况下，U1 snRNP与5'和3'剪接位点都能特异性相互作用，并且这些ATP依赖性相互作用需要SC35。重要的是，U1 snRNP与3'剪接位点之间依赖于SC35的相互作用需要U2 snRNP，但不需要5'剪接位点。我们还表明，SC35是U2 snRNP与分支点序列之间ATP依赖性相互作用所必需的。我们得出结论，SC35可能在介导与5'和3'剪接位点结合的剪接成分之间的特异性相互作用中发挥重要作用。
