Makarov Evgeny M, Makarova Olga V, Urlaub Henning, Gentzel Marc, Will Cindy L, Wilm Matthias, Lührmann Reinhard
Department of Cellular Biochemistry, Max Planck Institute of Biophysical Chemistry, D-37077 Göttingen, Germany.
Science. 2002 Dec 13;298(5601):2205-8. doi: 10.1126/science.1077783. Epub 2002 Oct 31.
Major structural changes occur in the spliceosome during its activation just before catalyzing the splicing of pre-messenger RNAs (pre-mRNAs). Whereas changes in small nuclear RNA (snRNA) conformation are well documented, little is known about remodeling of small nuclear ribonucleoprotein (snRNP) structures during spliceosome activation. Here, human 45S activated spliceosomes and a previously unknown 35S U5 snRNP were isolated by immunoaffinity selection and were characterized by mass spectrometry. Comparison of their protein components with those of other snRNP and spliceosomal complexes revealed a major change in protein composition during spliceosome activation. Our data also suggest that the U5 snRNP is dramatically remodeled at this stage, with the Prp19 complex and other factors tightly associating, possibly in exchange for other U5 proteins, and suggest that after catalysis the remodeled U5 is eventually released from the postsplicing complex as a 35S snRNP particle.
在催化前体信使核糖核酸（pre-mRNA）剪接之前的激活过程中，剪接体发生了重大的结构变化。虽然小核RNA（snRNA）构象的变化已有充分记录，但对于剪接体激活过程中小核糖核蛋白（snRNP）结构的重塑却知之甚少。在这里，通过免疫亲和选择分离出人类45S激活剪接体和一种此前未知的35S U5 snRNP，并通过质谱对其进行表征。将它们的蛋白质成分与其他snRNP和剪接体复合物的蛋白质成分进行比较，揭示了剪接体激活过程中蛋白质组成的重大变化。我们的数据还表明，U5 snRNP在此阶段发生了显著重塑，Prp19复合物和其他因子紧密结合，可能是与其他U5蛋白进行交换，并表明催化作用后，重塑的U5最终作为35S snRNP颗粒从剪接后复合物中释放出来。
