Insight into the mechanisms and functions of spliceosomal snRNA pseudouridylation

Figure 2 The splicing reaction. A: Steps of the spliceosome-mediated splicing reaction. The thick lines represent the intron and the boxes are exons. The short lines between RNA strands represent watson-crick base-pairing interactions. The 2'-OH groups of branch point adenosine and the cut-off 5' exon are pictured in the activated spliceosomes. The lightning symbols depict a nucleophilic attack that causes a transesterification reaction; B: Putative RNA-RNA hybrids formed during the splicing reaction.