H3K27ac

H3K27ac is a modification to DNA packaging protein Histone H3. It involves the acetylation at the 27th lysine residue of the histone H3 protein. H3K27ac is associated with the higher activation of transcription and therefore defined as an active enhancer mark. H3K27ac is found at both proximal and distal regions of transcription start site (TSS). Since the H3K27ac and H3K27me3 modification is at the same location on the histone tail, they antagonize each other. H3K27ac is often used to find active enhancers and poised enhancers subtracting from another enhancer mark H3K4me1 that contains all enhancers.