Fig. 2.

Phylogenetic analysis of Frizzled-related Cysteine-rich domains identifies a conserved lophotrochozoan gene complement. Cysteine-rich domains (CRDs) of frizzled transmembrane receptors and secreted frizzled-related proteins were aligned with MAFFT and analyzed with Mr Bayes. Posterior probabilities greater than 70 % are shown. The CRD of smoothened was used as an outgroup (not shown). Groupings of frizzled and sFRP subfamilies are highlighted with colored boxes. Platynereis dumerilii proteins are highlighted in red font, and cluster within frizzled subgroups with high posterior probability. Lophotrochozoan/Spiralian frizzled-related proteins are underlined. The novel Platynereis dumerilii protein FzCRD-1 clusters with the sFRP3/4 and vertebrate specific Fz3/6 subgroups with high posterior probability. The scale bar indicates the estimated number of substitution per site. The highly derived CRDs of Platynereis dumerilii sFRP3/4, FzCRD-2, and -3 were removed from this analysis. Species abbreviations: Ac, Aplysia californica; Cg, Crassostrea gigas; Ct, Capitella teleta; Dp, Daphnia pulex; Dr, Danio rerio; Hr, Helobdella robusta; Hs, Homo sapiens; Lg, Lottia gigantea; Nv, Nematostella vectensis; Pd, Platynereis dumerilii; Sk, Saccoglossus kowalevskii; Tc, Tribolium castaneum; Xl, Xenopus laevis