Chiara M D, Champion-Arnaud P, Buvoli M, Nadal-Ginard B, Reed R
Department of Cardiology, Children's Hospital, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1994 Jul 5;91(14):6403-7. doi: 10.1073/pnas.91.14.6403.
Spliceosome-associated proteins (SAPs) 61, 62, and 114 can be UV-crosslinked to pre-mRNA in purified spliceosomal complexes and are associated with U2 small nuclear ribonucleoproteins (snRNP). These proteins also compose the essential heterotrimeric splicing factor SF3a, and products of yeast pre-mRNA processing genes PRP9, PRP11, and PRP21 are their likely yeast counterparts. We report the isolation of a cDNA encoding SAP 61 and find that it is 30% identical in amino acid sequence to PRP9. A C-terminal Cys2His2 zinc-finger-like motif, which could be involved in the pre-mRNA binding, is the most highly conserved region of the protein. We also demonstrate specific protein-protein interactions between SAPs 61 and 114 and show that the N terminus of SAP 61 is required for this interaction. Significantly, the corresponding proteins are also known to interact in yeast: PRP9 interacts with PRP21, and the N-terminal portion of PRP9 is required. Previous work showed that direct interactions also occur between SAPs 62 and 114 and between the corresponding PRPs 11 and 21. These observations indicate that the specific protein-protein interactions that occur between the three prespliceosomal factors have been conserved between yeast and mammals.
剪接体相关蛋白（SAPs）61、62和114可在纯化的剪接体复合物中与前体mRNA进行紫外线交联，并与U2小核核糖核蛋白（snRNP）相关联。这些蛋白还构成了必需的异源三聚体剪接因子SF3a，酵母前体mRNA加工基因PRP9、PRP11和PRP21的产物可能是它们在酵母中的对应物。我们报告了编码SAP 61的cDNA的分离，并发现其氨基酸序列与PRP9有30%的同一性。一个可能参与前体mRNA结合的C末端Cys2His2锌指样基序是该蛋白中保守性最高的区域。我们还证明了SAPs 61和114之间存在特异性的蛋白质-蛋白质相互作用，并表明这种相互作用需要SAP 61的N末端。值得注意的是，已知相应的蛋白在酵母中也会相互作用：PRP9与PRP21相互作用，且需要PRP9的N末端部分。先前的工作表明，SAPs 62和114之间以及相应的PRPs 11和21之间也会发生直接相互作用。这些观察结果表明，酵母和哺乳动物之间，三种剪接体前体因子之间发生的特异性蛋白质-蛋白质相互作用是保守的。
