Fig. 1.

HD protein logo generated primarily from Drosophila HD proteins (Sup. Fig. S1) using LogoBar (Pérez-Bercoff Å and Bürglin 2010; Pérez-Bercoff et al. 2006). The higher the bar, the stronger a position is conserved. Letters inside the bars indicate amino acid residues. Open bars indicate gap regions that were introduced to accommodate longer atypical HDs. Numbers underneath are based on the standard numbering for HDs with 60 residues, and “abc” marks the positions of the three extra residues in loop 1 of TALE HDs. The three alpha helices are indicated with shaded boxes. At the bottom, the consensus sequence (most frequent residue) is shown; residues underneath each position are listed in decreasing order of frequency of occurrence