Primary Citation of Related Structures:   5YZG
PubMed Abstract: 
Splicing by the spliceosome involves branching and exon ligation. The branching reaction leads to the formation of the catalytic step I spliceosome (C complex). Here we report the cryo-electron microscopy structure of the human C complex at an average resolution of 4.1 angstroms. Compared with the Saccharomyces cerevisiae C complex, the human complex contains 11 additional proteins. The step I splicing factors CCDC49 and CCDC94 (Cwc25 and Yju2 in S. cerevisiae , respectively) closely interact with the DEAH-family adenosine triphosphatase/helicase Prp16 and bridge the gap between Prp16 and the active-site RNA elements. These features, together with structural comparison of the human C and C* complexes, provide mechanistic insights into ribonucleoprotein remodeling and allow the proposition of a working mechanism for the C-to-C* transition.
Organizational Affiliation: 
Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China. yancy05@mails.tsinghua.edu.cn shi-lab@tsinghua.edu.cn.
Technology Center for Protein Sciences, Ministry of Education Key Laboratory of Protein Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China.
Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Shilongshan Road No. 18, Xihu District, Hangzhou 310064, Zhejiang Province, China.