Positive selection in alternatively spliced exons of human genes.

摘要: Alternative splicing is a well-recognized mechanism of accelerated genome evolution. We have studied single-nucleotide polymorphisms and human-chimpanzee divergence in the exons 6672 alternatively spliced human genes, with aim understanding forces driving evolution sequences. Here, we show that exon fragments (alternative exons) from minor isoforms experience lower selective pressure at amino acid level, accompanied by selection against synonymous sequence variation. The results McDonald-Kreitman test suggest exons, unlike constitutively included mRNA, are also subject to positive selection, up 27% acids fixed selection.