Over-representation of exonic splicing enhancers in human intronless genes suggests multiple functions in mRNA processing.
The human transcriptome is constituted of a great majority of intron-containing and a minority of intron-lacking mRNAs; given the different processing these transcripts undergo, they are expected to carry, intermingled with coding properties, very different editing information. Here we applied a computational approach to compare intronless and intron-containing coding sequences. Hexamer composition comparison allowed the definition of over- and under-represented motifs in intronless genes; surprisingly, experimental testing revealed that intron-lacking coding sequences are enriched rather than depleted in elements with splicing enhancement ability. Similarly, we show evidence that intronless transcripts display a significantly higher frequency of both shuttling and non-shuttling SR protein binding sites compared to intron-containing sequences. These observations suggest that SR proteins (and possibly other splicing factors) play a role in cellular processes distinct from splicing.
Scientific Institute IRCCS E. Medea, Associazione La Nostra Famiglia, 23842 Bosisio Parini (LC), Italy. upozzoli@bp.lnf.it
Uberto
U
Pozzoli
Laura
L
Riva
Giorgia
G
Menozzi
Rachele
R
Cagliani
Giacomo P
GP
Comi
Nereo
N
Bresolin
Roberto
R
Giorda
Manuela
M
Sironi
D001483:Base Sequence; D004742:Enhancer Elements, Genetic; D005091:Exons / Q000235:genetics*; D006801:Humans; D007438:Introns / Q000235:genetics*; D008969:Molecular Sequence Data; D012326:RNA Splicing / Q000235:genetics / Q000502:physiology*; D017422:Sequence Analysis, DNA