Multiple alignment of the binding sites of orthologous introns showing conservation and drift. (a) The sequence 5'-GGCAGUUUUCAA-3' upstream of exon 6.25 of Drosophila melanogaster is perfectly conserved in the orthologous exons (Table 1) across all species. (b) The binding sequence upstream of exon 6.48 of D. melanogaster drifts into different binding sequences in the orthologous exons of other species. Areas indicated in red are the predicted binding sites.
Anastassiou et al. Genome Biology 2006 7:R2 doi:10.1186/gb-2006-7-1-r2