Spt-Ada-Gcn5 acetyltransferase (SAGA) is a histone modifying transcriptional co-activator that is composed of 21 proteins and exhibits histone acetyltransferase (HAT) and deubiquitinating (DUB) activity. In yeast the SAGA complex serves to activate the transcription of approximately 10% of the genome, and this active gene/SAGA complex is then able to interact with the TREX-2 complex, a NPC-associated mRNA export complex. Numerous proteins involved in the formation of mRNA interact with the NPC, with the majority of these protein-protein interactions occurring between the SAGA complex and the TREX-2 complex at the NPC. Correct transcription and subsequent export of mRNA is largely dependent on this interaction. A common protein subunit of both the SAGA and TREX-2 complexes, Sus1, binds to the upstream activating sequence via SAGA, which then serves as the attachment point to the TREX-2 complex. The interacting surfaces between Sus1 and the TREX-2 complex are facilitated by the protein subunits Mex67 and Yra1 of the TREX-2 complex, as evidenced by co-immunoprecipitation experiments. The TREX-2 complex is bound to the NPC complex by the nucleoporin Nup1. All TREX-2 subunits are necessary for the successful formation and export of an mRNA transcript at the nuclear membrane for genes activated by the SAGA complex, and data suggest that SAGA and TREX-2 act in concert to recruit Sus1 to genes to be transcribed. Other investigations have shown that several SAGA subunits interact with the NPC protein Mlp1, providing another link between the NPC and the SAGA/active gene complex.