期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2007
卷号：104
期号：9
页码：3195-3200
DOI：10.1073/pnas.0611591104
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The spliceosome is a dynamic macromolecular machine that catalyzes the excision of introns from pre-mRNA. The megadalton-sized spliceosome is composed of four small nuclear RNPs and additional pre-mRNA splicing factors. The formation of an active spliceosome involves a series of regulated steps that requires the assembly and disassembly of large multiprotein/RNA complexes. The dynamic nature of the pre-mRNA splicing reaction has hampered progress in analyzing the structure of spliceosomal complexes. We have used cryo-electron microscopy to produce a 29-A density map of a stable 37S spliceosomal complex from the genetically tractable fission yeast, Schizosaccharomyces pombe. Containing the U2, U5, and U6 snRNAs, pre-mRNA splicing intermediates, U2 and U5 snRNP proteins, the Nineteen Complex (NTC), and second-step splicing factors, this complex closely resembles in vitro purified mammalian C complex. The density map reveals an asymmetric particle, {approx}30 x 20 x 18 nm in size, which is composed of distinct domains that contact each other at the center of the complex.
