Phylogenetic relationship of PKR and PKZ genes. The phylogenetic tree was constructed from the kinase domains of PKR (blue branches) and PKZ (red branches), omitting the KI, using maximum likelihood and BMCMC approaches. Both analyses resulted in the same tree topology. Significant bootstrap values above 70 (for maximum likelihood analysis) and significant posterior probabilities converted to percentages above 95 (for Bayesian analysis) are shown above and below the branches, respectively. Asterisks denote evident duplication events. Human and zebrafish PERK were used as outgroups for rooting the phylogenetic tree. The following abbreviations were used: Bt, Bos taurus (cattle); Ss, Sus scrofa (pig); Cf, Canis familiaris (dog); Oc, Oryctolagus cuniculus (European rabbit); Ec, Equus caballus (horse); Mam, Macaca mulatta (Rhesus macaque); Cae, Chlorocebus aethiops (African green monkey); Pt, Pan troglodytes (chimpanzee); Hs, Homo sapiens (human); Mm, Mus musculus (house mouse); Rn, Rattus norvegicus (Norway rat); Ma, Mesocricetus auratus (golden hamster); Oa, Ornithorhynchus anatinus (platypus); Md, Monodelphis domestica (gray short-tailed opossum); Gg, Gallus gallus (chicken); Xt, Xenopus tropicalis (western clawed frog); Xl, Xenopus laevis (African clawed frog); Tn, Tetraodon nigroviridis (green spotted pufferfish); Tr, Takifugu rubripes (torafugu); Ga, Gasterosteus aculeatus (three spined stickleback); Ol, Oryzias latipes (Japanese medaka); Dr, Danio rerio (zebrafish); Pp, Pimephales promelas (fathead minnow); Ca, Carassius auratus (goldfish); Ssa, Salmo salar (Atlantic salmon).