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. Author manuscript; available in PMC: 2015 Feb 21.
Published in final edited form as: Chem Soc Rev. 2013 Aug 22;43(4):1189–1200. doi: 10.1039/c3cs60208g

Figure 5.

Figure 5

Pre-mRNAs contain introns (lines) that are removed by the spliceosome along with concomitant ligation of protein-coding exons (boxes) to produce mRNAs. The major subcomplexes of the spliceosome (the U1 and U2 snRNPs, the U4/U6.U5 tri-snRNP, and the protein-only NTC) assemble stepwise on each intron to carry out the splicing reaction with the help of a number of additional trans-acting factors (not shown).