Introns in UTRs: why we should stop ignoring them.

Although introns in 5'- and 3'-untranslated regions (UTRs) are found in many protein coding genes, rarely are they considered distinctive entities with specific functions. Indeed, mammalian transcripts with 3'-UTR introns are often assumed nonfunctional because they are subject to elimination by nonsense-mediated decay (NMD). Nonetheless, recent findings indicate that 5'- and 3'-UTR intron status is of significant functional consequence for the regulation of mammalian genes. Therefore these features should be ignored no longer.