Transposable elements are found in a large number of human protein-coding genes

To study the genome-wide impact of transposable elements (TES) on the evolu tion of protein-coding regions, we examined 13 799 human genes and found 53 3 (similar to4%) cases of TIES within protein-coding regions. The majority of these TEs (similar to 89.5%) reside within 'introns' and were recruited into coding regions as novel exons. We found that TE integration often has an effect on gene function. In particular, there were two mouse genes whose coding regions consist largely of TES, suggesting that TE insertion might create new genes. Thus, there is increasing evidence for an important role of TEs in gene evolution. Because many TEs are taxon-specific, their integr ation into coding regions could accelerate species divergence.