Figure 1. Reversible post-translational modification (PTM) ubiquitination of H2A (K119) and H2B (K120) on specific amino acid residues on core histone tails regulates various biological processes, including transcription elongation, inflammation, DNA replication, and DNA DSB repair processes, and is highly dynamic in nature.

These modifications are added on to histones by RNF20/40 E3 ubiquitin ligases. These PTM marks are identified and removed by active enzymes known as deubiquitinating enzymes. Any deregulation of this process often leads to malignant cellular transformation.