Perturbation of transcription elongation influences the fidelity of internal exon inclusion in Saccharomyces cerevisiae

A model showing how relative rates of elongation and intron recognition can lead to exon skipping or inclusion. Factors that affect the relative rates of spliceosome assembly and transcript elongation will influence the amount of time available for establishment of splice site pairing as in (A), which will lead to exon inclusion. Slow recognition of the first intron or rapid transit of polymerase through the second intron provides a greater opportunity for exon skipping, as in (B).