Sites of predicted positive selection in the transcriptional activation domains of CBF1, -2, and -3. The figures were modified according to Figure 3B of Wang et al. . Ninety-eight amino acids of the CBF1 C-terminal were aligned with the same domains of CBF2 and -3 (Col ecotype). The numbers above the upper panel are amino acid numbers of the protein sequence alignment. Six hydrophobic clusters are labeled by a line above each cluster, and hydrophobic residues within clusters are indicated by black blocks. Reporter constructs possessing an alanine-substituted CBF1 activation domain were used to estimate the contribution of motifs or residues to transactivation activity. The alanine-substituted residues are indicated by black underlining below each site, and the percentages of changes in reporter enzyme (β-galactosidase) activity related to the wild-type CBF1 activation domain construct are indicated just below each underlined alanine substitution. Sequences boxed by rectangles indicate regions which had the highest Ka/Ks ratios in the transcriptional activation domains in Figure 4A. Gray blocks covering amino acid sequences indicate regions in which the Ka/Ks ratios exceed 1 using a non-overlapping sliding window method (i.e., the gray block covering residue sites 137 to 142 representing this region of six residues was detected in the comparison of CBF1 and -3). There are three pair-wise comparisons between CBF1, -2, and -3, and four regions were labeled by gray blocks.