Fig. 2From: Epigenomics of mammary gland developmentEpigenetic regulation of chromatin structure. The majority of DNA is packaged into inactive heterochromatin which is marked by repressive histone marks H3K27Me3, H3K9Me3, H2AK119Ub, and methylated CpG islands (closed circles) in gene promoters. Regions of open chromatin allow for activation of gene transcription and are marked by active histone marks H3K4Me3 and general histone acetylation as well as unmethylated CpG islands (open circles) in gene promoters and methylation of gene bodies. Promoter-enhancer looping (not shown) is another layer of epigenetic regulation of gene expressionBack to article page