Phylogenetic analysis of the PRKX, PKA, PKC, protein kinase B
(PKB), cGMP protein kinases, and serum- and glucocorticoid-inducible
kinase (SGK)-related kinase families. The catalytic domains of the most
highly PRKX homologous human, nematode, yeast,
Dictyostelium, and D.
melanogaster protein kinases identified by
BLAST search were aligned with
CLUSTALW
(http://workbench.sdsc.edu/CGI/BW.cgi) to generate an unrooted
phylogenetic tree with PHYLIP 3.5C (46). Protein
kinase Y (PRKY, GenBank accession no. CAA75792) was excluded, because
it lacks 81 C-terminal amino acid residues essential for kinase
activity (47). The PKC family was added to the phylogenetic analysis as
an outgroup (48). Except for the SGK kinase (from Rattos
norvegicus) and mouse PRKX, all mammalian kinases used
in this analysis were the human orthologs (see Table 2, which is
published as supporting information on the PNAS web site,
www.pnas.org). The PKA-α kinase is indicated by an asterisk, and
human PRKX is underlined.