The activity of transcription factors is often regulated by Post-translational modifications. A precondition for such modifications is the presence, in the corresponding mRNAs, of the exons that either directly encode the modifiable residues in question, or encode protein domains that influence their modification indirectly. The inclusion or exclusion of coding exons is regulated predominantly by alternative splicing but can also depend on promoter choice and polyadenylation site selection. Information about exon inclusion and exclusion, both qualitatively and quantitatively, is particularly important for experiments designed to mutate endogenous codons because such mutations can alter splicing patterns. Therefore, we here describe methods employed to quantitate exon inclusion and exclusion, using as example a mouse transcription factor gene,Mitf.
