(Bern5 @ 09.12.2016 19:00)
UTRs
5′ and 3′ untranslated regions (UTRs) play important roles in translation, regulation, stability, and/or localization of mRNAs. When using a strict definition of regions encoding the final product of a protein-coding gene, these regions would no longer be considered part of the gene, as is often the case in current usage. Moreover, protein-coding transcripts that share DNA sequence only in their untranslated regions or introns would not be clustered together into a common gene. By removing UTRs from the definition of a gene, one can avoid the problem of multiple 5′ and 3′ ends clouding the delineation of the gene and also avoid a situation in which upstream or trans 5′ leader sequences are spliced onto a protein coding sequence. Moreover, it has been observed that most of the longer protein-coding transcripts identified by ENCODE differ only in their UTRs, and thus our definition is quite transparent to this degree of transcript complexity.