Fig. 3

Evolution of Prickle and Testin from an ancestral PkTesL protein without a long C-terminal tail. Functional domain analyses and phylogenetic trees of Prickle (Pk) and Testin (Tes) show the long C-terminal tail of Pk compared to Tes (a). The position of each protein in the tree has been determined by ML and Bayesian phylogenetic analyses (Additional file 2). A unique and ancestral Prickle/Testin-like protein (retrieved in Porifera and Ctenophora: PkTesL) is presumed to have given birth to Pk and Tes proteins (retrieved in Bilateria, Cnidaria and Placozoa) (b). The tail was added at the C-terminal end of Pk before the split between ctenophores and (cnidarians + bilaterians). Tes was then secondarily lost in placozoans (not represented). Abbreviations. Bilateria: Dm, Drosophila melanogaster and Mm, Mus musculus. Cnidaria: Ch, Clytia hemisphaerica and Nv, Nematostella vectensis. Placozoa: Trichoplax adhaerens. Porifera: Aq, Amphimedon queenslandica; Av, Aphrocalistes vastus; Em, Ephydatia muelleri; Oc, Oscarella carmela; Ol, Oscarella lobularis; Om, Oopsacas minuta; Osp, Oscarella sp. and Sc, Sycon ciliatum. Ctenophora: Mnemiopsis leidyi. Choanoflagellata: Sr, Salpingoeca rosetta. Scale: 200 amino-acids