Illustration of a potential mechanism for the selection of exon 17. When the stem from the blue sequences is implemented, it potentially obstructs the splicing branch point of intron 16-17.1 inhibiting the selection of exon 17.1 and resulting in the selection of exon 17.2. If the competing stem from the red sequences is implemented, then, under the additional assumption that a pseudoknot involving both interactions is not implemented, exon 16 is allowed to be spliced directly into exon 17.1.
Anastassiou et al. Genome Biology 2006 7:R2 doi:10.1186/gb-2006-7-1-r2