Figure 1.

Writers, erasers and readers. The basic functional unit of chromatin is the nucleosome, which is composed of DNA wrapped around histones (H2A, H2B, H3 and H4). Core histone tails are projected from nucleosomes and are subject to PTMs. These include methylation (Me), acetylation (Ac), phosphorylation (Ph) and ubiquitination (Ub). The main epigenetic regulators can be categorized as writers, erasers and readers of PTMs. Epigenetic writers are responsible for the addition of chemical modifications. Epigenetic erasers catalyse the removal of the covalent modifications. Epigenetic readers are proteins with specific domains that recognize and bind to particular modifications.