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Fig. 2. Radial phylogenetic trees for selected stress proteins of four species from
three super-kingdoms. Sequence comparisons were made with ClustalW
(http://www.ebi.ac.uk/clustalw)
and phylogenetic trees visualized using TreeView 1.6
(http://taxonomy.zoology.gla.ac.uk/rod/rod.html).
Each sequence is labeled with their GenBank accession number. The length of
the lines connecting individual sequences represents evolutionary distance,
which is based on the degree of sequence similarity between paralogues. The
examples shown illustrate that genes encoding stress proteins were subject to
adaptive radiation at different times during the evolution of life, which
presumably reflects their increasing role for multiple important cell
functions. Other very important stress response genes such as
mitogen-activated protein kinases (MAPKs) and 14-3-3 proteins display similar
patterns of late adaptive radiation in eukaryotes as shown for the DNA
mismatch repair factor MSH/mutS. In contrast to the latter, however, MAPKs and
14-3-3 proteins have originated in eukaryotes and are entirely absent from
prokaryotes, whose phosphorylation-based signaling systems differ greatly from
those in eukaryotes.
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