The export of messenger RNA from nucleus to cytoplasm is an essential process in eukaryotic cells. Sus1 protein plays a significant role in the coupling between the initiation of transcription and mRNA export. Sus1 is a small protein (11kDa of only), conserved in eukaryotes that physically interacts with two stable multiprotein complex. Sus1 binds to the transcription activator complex SAGA and the complex formed by TREX2 binding proteins nuclear pore. In previous studies the group of Rodriguez-Navarro, Sus1 identified that is part of a submodule of SAGA, comprising Sus1-Ubp8-Sgf1, and responsible for deubicuitinación of histone H2B.

In this new work published in Genes and Development, Sus1 show that not only binds to the promoter regions of genes and the nuclear pore, but is present in coding regions dependent manner the action of RNA polymerase II. They have managed to determine that the mutant Sus1 serious defects in transcriptional elongation, suggesting a role for Sus1 not only in transcriptional activation coupled to mRNA export, but also during the biogenesis of mRNA. They have also found that Sus1 physically interacts with RNA polymerase II phosphorylated and export the key factors Yra1 and Mex67.

By chromatin binding studies show that Sus1 is present in the coding regions and that this binding is mediated by the SAGA complex and the complex TREX2. They have also identified component of SAGA Sgf73 (ataxin 7 in humans) as a crucial factor in the function module Sus1 and deubicuitinación. The results of this work have allowed Sus1 relate more directly to the biogenesis of mRNA.