Role of Sug1, a 19S proteasome ATPase, in the transcription of MHC I and the atypical MHC II molecules, HLA-DM and HLA-DO

► Sug1 is required for optimal gene expression of MHC I, and the atypical MHC II proteins HLA-DM and HLA-DO. ► Sug1 binds directly and specifically to the HLA promoters. ► Histone H3 acetylation at the HLA promoters decreases in the absence of Sug1. ► Sug1 is essential for CBP and CIITA recruitment to the MHC promoters.