TF binding depends on sequence determinants both within and outside core TFBSs. (A, left) The sorted binding scores computed for ∼6000 sequences in an experiment with Gcn4 are shown in dark blue. The number of strong Gcn4 TFBSs, weak Gcn4 TFBSs, and Gal4 TFBSs in each corresponding sequence is shown in light blue in the following panels. (B) Same as in A, but for an experiment carried out with Gal4. (C) For sequences with either no mutations or with single, double, and triple mutations in the Gcn4 core binding site, expression measurements (left) (adapted from Sharon et al. 2012 with permission from Nature Publishing Group © 2012) and the Gcn4 binding score (right) are shown. (D) The binding score for a sequence with a strong Gcn4 site (top) and for a corresponding sequence with a single mutation in the binding site (bottom) is shown in dark blue. The binding score of more than 1000 sequences with the same single strong binding site, differing in the location and context in which the site is embedded, is shown in gray (sequences are sorted by their score), spanning the range attained by a single destructive mutation within the site.
