Comparing PBS and peak calling in H3K27ac and H3K27me3 datasets.

(A) Histogram of read-counts and PBS (inset) for a representative H3K27ac dataset. (B) Venn diagram describing overlap between bins with high PBS and bins with peaks in (A). (C) Histogram of read-counts and PBS (inset) for a representative H3K27me3 dataset. (D) Venn diagram describing overlap between bins with high PBS and bins in (C). In both (A) and (C), the black curve corresponds to the background distribution estimated from a fit to bottom fiftieth percentile of data. The heavier tail and greater number of bins with PBS > 0 in (C) compared to (A) indicate elevated genome-wide enrichment of H3K27me3 when compared to H3K27ac. Venn diagrams to the right of the histograms indicate the overlap between bins containing peaks and those with PBS > 0.9 for each histone mark.