The effect of local dinucleotide background frequency correction on cumulative TF scores within several kilobases of the TSS. (Left panels) VDR (vitamin D receptor) is typical of a relatively GC-rich motif that shows score enrichment in the TSS vicinity partly due to an increasingly GC-rich background near many TSS, and partly due to a sharp locally enriched signal, which can often be difficult to distinguish as a separate entity. (Right panels) TEF (thyrotrophic embryonic factor) is typical of a relatively AT-rich motif that shows depletion in the TSS vicinity for the same reason. The local background correction decouples specific local signal enrichment from broader enrichment arising because of the interplay between TF motif composition and background composition. TRANSFAC ID for each binding element is displayed in plot titles.
