The NSD family of HMTase. A- The schematic primary structure of NSD1, NSD2, and NSD3: All NSD members contain two PWWP domains, four PHD zinc finger domains, and a CD. The CD has HMTase activity and contains the pre-SET, SET, and post-SET domains. The regulatory loop over the histone-binding site is indicated in red. B- Coomassie Blue staining of a SDS-PAGE gel confirms the expressed recombinant NSD1-CTD, NSD2-CTD, and NSD3-CTD.