Figure 1.
Multiple RNA variables contribute to the production of distinct isoforms from the same gene. In alternative exon inclusion, an exon can be either included or spliced out of a transcript. In alternative TSS usage, transcription can start at two different positions. In alternative poly(A) site usage, the 3′ untranslated region can vary in length. In alternative donor or acceptor site usage, the boundary between an exon and an intron can shift. In intron retention, an intron can be included in the mature mRNA.
