Figure 4.

A series of Venn diagrams showing the relationship between exon class and coding potential. An exon may be fully protein coding, partially protein coding, or be fully UTR. An exon may be a part_of a single transcript gene (single-transcript genes), be a part_of either one (UNIQUE exons), all (ALWAYS_FOUND exons), or a fraction (SOMETIMES_FOUND exons) of transcripts in an alternatively transcribed gene.