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. Author manuscript; available in PMC: 2018 Mar 1.
Published in final edited form as: Wiley Interdiscip Rev RNA. 2016 Jul 21;8(2):10.1002/wrna.1381. doi: 10.1002/wrna.1381

Figure 2. Splicing inhibitors may impact competition between splicing substrates in cells.

Figure 2

Different splice sites in pre-mRNA substrates (indicated by differently shaded exons flanking introns) compete for the spliceosome (ssome). Competitiveness is determined by a combination of splice site (SS) sequence strength, the presence of positive alternative splicing factors (alt SF) and total amount of pre-mRNA transcript (indicated by pre-mRNA size). Under normal cellular conditions (left panel) the weakest competitors "lose" for splicing (not engaged by ssome), typically resulting in alternative splicing changes. With splicing inhibitors (red and white "no" sign) additional splice sites will lose for splicing (right panel), resulting in alternative splicing changes and intron retention. Splicing events required for a cells growth (golden pre-mRNAs) will drive the response to the splicing inhibitor. Importantly, the relative competitiveness of an intron will differ in different cell types and under different conditions because the presence of alternative splicing factors differ along with pre-mRNA transcript levels.