The magnitude and effect of sensu stricto TF binding sites variation. (A) Mean sensu stricto sequence conservation of positions within annotated TF binding sites (in blue) (see Supplemental Note) and of their flanking positions (in red, double the length of the binding site). For each TF, each position of its motif logo appears below the mean conservation of that position. For all TFs, conservation of TF binding site positions was significantly higher than that of flanking positions (rank-sum P-values written in blue). (B) Sensu stricto TF binding site variation (see Supplemental Note) versus promoter activity variation (the coefficient of variation of the four orthologous promoter activities).
