Component of the transcription regulatory histone acetylation (HAT) complex SAGA, a multiprotein complex that activates transcription by remodeling chromatin and mediating histone acetylation and deubiquitination. Within the SAGA complex, participates in a subcomplex that specifically deubiquitinates both histones H2A and H2B (PubMed:18206972, PubMed:21746879). The SAGA complex is recruited to specific gene promoters by activators such as MYC, where it is required for transcription. Required for nuclear receptor-mediated transactivation. Within the complex, it is required to recruit USP22 and ENY2 into the SAGA complex (PubMed:18206972). Regulates H2B monoubiquitination (H2Bub1) levels. Affects subcellular distribution of ENY2, USP22 and ATXN7L3B (PubMed:27601583). Component of some SAGA transcription coactivator-HAT complexes, at least composed of ATXN7, ATXN7L3, ENY2, GCN5L2, SUPT3H, TAF10, TRRAP and USP22. Within the SAGA complex, ENY2, ATXN7, ATXN7L3, and USP22 form an additional subcomplex of SAGA called the DUB module (deubiquitination module) (PubMed:18206972, PubMed:21746879, PubMed:27601583). Interacts directly with ENY2 and USP22 (PubMed:18206972). The long N-terminal helix forms part of the 'assembly lobe' of the SAGA deubiquitination module. The C-terminal SGF11-type zinc-finger domain together with the C-terminal catalytic domain of USP22 forms the 'catalytic lobe' of the SAGA deubiquitination module. Belongs to the SGF11 family.