Involved in mRNA export coupled transcription activation by association with both the TREX-2 and the SAGA complexes. At the promoters, SAGA is required for recruitment of the basal transcription machinery. It influences RNA polymerase II transcriptional activity through different activities such as TBP interaction and promoter selectivity, interaction with transcription activators, and chromatin modification through histone acetylation and deubiquitination. Within the SAGA complex, participates in a subcomplex required for deubiquitination of H2B and for the maintenance of steady-state H3 methylation levels. The TREX-2 complex functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket). TREX-2 participates in mRNA export and accurate chromatin positioning in the nucleus by tethering genes to the nuclear periphery. May also be involved in cytoplasmic mRNA decay by interaction with components of P-bodies (By similarity). Component of the nuclear pore complex (NPC)-associated TREX-2 complex (transcription and export complex 2), composed of at least sus1, sac3, thp1, sem1, and cdc31. TREX-2 contains 2 sus1 chains. The TREX-2 complex interacts with the nucleoporin nup1. Component of the 1.8 MDa SAGA transcription coactivator-HAT complex. SAGA is built of 5 distinct domains with specialized functions. Within the SAGA complex, sus1, sgf11, sgf73 and ubp8 form an additional subcomplex of SAGA called the DUB module (deubiquitination module). Interacts directly with thp1, sac3, sgf11, and with the RNA polymerase II. Belongs to the ENY2 family.