Fig. 10

Evolutionary changes in exon-intron structure of arrestins. a - Exon-intron structure of the bovine ARRB1 gene. Exon and intron numbering is imposed onto arrestin homologs by sequence alignment. Positions of introns refer to their position on the amino acid sequence of cow arrestin-2 with a-c indicating their position after the first, second or third base of the codon, respectively. b - Exon-intron structure of arrestins (right hand side) is associated with a simplified gene tree (left hand side). Exons are shown as grey and colorful boxes, whereby homologous regions are “aligned” below each other. Colored exons highlight differences in exon-intron structure (intron gain, intron loss, exon loss). Changes in intron positions in comparison to the reference amino acid sequence of cow arrestin-2 are given whenever deviating except for the positions surrounding exons 13 and 15, which occasionally deviated by few nucleotides in our annotation (see Additional file 1: Appendix 7). Information about the corresponding exons was not available in the genomes if boxes are surrounded by a dotted line, but are assumed to be the same as in the 1:1 ortholog of the closest relative. If an unequivocal scenario of intron loss or gain is in accordance with the maximum parsimony principle, these events are indicated in the phylogenetic tree. Paralogs of species that share the exon-intron structure are summarized to phylogenetic clades, e.g. ARRB1 vertebrates. Structural differences in comparison to the family are shown right below associated with the corresponding species or phylogenetic clade. Losses of coding sequence (exons) are indicated by black pentagons with respective exons given as a number in the pentagon. The phylogenetic tree was created using Treegraph 2.0.54 [114]. c - Exon-intron structure of lamprey arrestins. Note that the length of the exon boxes is drawn to scale