Fig. 3

Multiple alignment of the functional domains in the Dbx protein family. a Multiple alignment of representative sequences of the Dbx family allowed the identification of a RD1 (blue) in all species with the exception of the tunicate Ciona intestinalis and the crustacean Daphnia pulex. RD2 (red) is found in all Dbx and Dbx1 sequences, but not in Dbx2 proteins. A specific enrichment and clusterization of acidic residues (green) is found at the C-terminus of Dbx1 proteins of tetrapods as well as in Saccoglossus kowalevskii, Patiria miniata, Lingula anatina and Capitella teleta. b Phylogenetic tree of the species used in a. The orange box indicates species containing both Dbx1 and Dbx2 sequences, suggesting that the Dbx duplication occurred in the common ancestor to all gnathostomes. Pink boxes indicate species in which it was possible to find a stretch of 10 amino acids containing at least 80 % of D or E within the C-terminus