Co-regulation of transcription by pairs of histone modifications. (a) Categorization of genes into four groups based on signals of H3K4me3 and H3K36me3: HH (magenta), HL (green), LH (cyan) and LL (blue). The signals of histone marks H3K36me3 and H3K4me3 exhibit a bimodal feature. Signals are thus classified into H and L by a Gaussian mixture model. The distributions of expression levels of the four gene groups are shown on the right. (b) Same as (a), based on signals of H3K9me3 and H3K79me3. Same as above, the signal of H3K79me3 is again classified by a Gaussian mixture model. The signals of H3K9me3 do not display a bimodal feature; signals are classified into H and L based on whether the value is higher than or lower than the median.
Cheng et al. Genome Biology 2011 12:R15 doi:10.1186/gb-2011-12-2-r15