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. Author manuscript; available in PMC: 2014 Sep 4.
Published in final edited form as: RNA Biol. 2010 Mar 14;7(2):192–204. doi: 10.4161/rna.7.2.11207

Figure 1.

Figure 1

Major spliceosome assembly and catalysis of pre-mRNA splicing. The thick lines represent the intron and the boxes are exons. The 5' splice site (5'-SS), the 3' splice site (3'-SS) and the branch point adenosine (BP) are indicated in the pre-mRNA. The conserved residues at the 5' and 3' splice sites and the branch site are shown. The headed thin lines are snRNAs with their names in the ellipses. The short thick lines between RNA strands represent Watson-Crick base-pairing interactions. The lightning symbols depict non-Watson-Crick base-pairing interactions. The 2'-OH groups of branch point adenosine and the cut-off 5' exon are pictured in the activated spliceosome. The small arrows near those 2'-OH group indicate the nucleophilic chemical reactions also known as trans-esterification reactions.