Figure 3.

Asymmetric function of H2Bub1 deposition and deubiquitylation. H2B ubiquitination is associated with active RNA polymerase II transcription. H2Bub1 facilitates the trimethylation of H3K4 (the histone tail cross-talk is labeled with a red arrow). Removal of monoubiquitin (ub) from histone H2Bub1-containing nucleosomes by the ATXN7L3-dependent SAGA DUB module and the related ATXN7L3-regulated DUBs do not significantly affect the status of H3K4 trimethylation, or RNA polymerase II transcription. However, H2Bub1 deubiquitination does not recreate the original nucleosome state, but instead, could impact the levels of free ub in the cell.