Figure 1.

Known examples of overlapping translated ORFs. A) The second exon of the INK4A and ARF genes is shared but translated in different reading frames. B) A transcript fusion can occur between the MASK and EIF4EBP3 genes, via an intermediate exon. In this case, the next exon is translated in a different frame from that in EIF4EBP3 transcripts. C) A splice variation in IGF-1 can cause a frameshift in the translation of C-terminal residues. D) Exon 1 of the G-protein subunit XL-alpha-s contains a second, frameshifted tRF which yields a distinct protein called Alex. Grey shading indicates overlapping frameshifted ORFs, exons and tORFs are drawn approximately to scale.