H3K4me1 - mono-methylation of lysine 4 of H3. Activating mark (IHEC reference epigenome). This modification occurs at nucleosomes flanking transcription factor binding sites of enhancers. The enriched regions co-occurs in almost all promoters that are marked by H3K4me3; however, this mark has a broader distribution than H3K4me3. Many enriched locations coincide with distal enhancer sites in intergenic regions. Typically there are >100K of H3K4me1 enriched locations genome wide in humans. Enriched regions can be in a form of localized peaks as well as extended regions.
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