4trq | pdb_00004trq
Crystal structure of Sac3/Thp1/Sem1
Structural highlights
Function[SAC3_YEAST] Component of the SAC3-THP1 complex, which functions in transcription-coupled mRNA export from the nucleus to the cytoplasm. SAC3-THP1 functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket), by association with components of the nuclear mRNA export machinery (MEX67-MTR2 and SUB2) in the nucleoplasm and the nucleoporin NUP1 at the nuclear basket.[1] [2] [SEM1_YEAST] Versatile protein that might stabilize multiple protein complexes involved in diverse pathways. Subunit of the 26S proteasome which plays a role in ubiquitin-dependent proteolysis. Associates also with the TREX-2 complex that is required for transcription-coupled mRNA export, and the COP9 signalosome, which is involved in deneddylation.[3] [4] [THP1_YEAST] Component of the SAC3-THP1 complex, which functions in transcription-coupled mRNA export from the nucleus to the cytoplasm. SAC3-THP1 functions in docking export-competent ribonucleoprotein particles (mRNPs) to the nuclear entrance of the nuclear pore complex (nuclear basket), by association with components of the nuclear mRNA export machinery (MEX67-MTR2 and SUB2) in the nucleoplasm and the nucleoporin NUP1 at the nuclear basket. THP1 binds to RNA in vitro.[5] [6] [7] Publication Abstract from PubMedNuclear pore complexes (NPCs) influence gene expression besides their established function in nuclear transport. The TREX-2 complex localizes to the NPC basket and affects gene-NPC interactions, transcription, and mRNA export. How TREX-2 regulates the gene expression machinery is unknown. Here, we show that TREX-2 interacts with the Mediator complex, an essential regulator of RNA Polymerase (Pol) II. Structural and biochemical studies identify a conserved region on TREX-2, which directly binds the Mediator Med31/Med7N submodule. TREX-2 regulates assembly of Mediator with the Cdk8 kinase and is required for recruitment and site-specific phosphorylation of Pol II. Transcriptome and phenotypic profiling confirm that TREX-2 and Med31 are functionally interdependent at specific genes. TREX-2 additionally uses its Mediator-interacting surface to regulate mRNA export suggesting a mechanism for coupling transcription initiation and early steps of mRNA processing. Our data provide mechanistic insight into how an NPC-associated adaptor complex accesses the core transcription machinery. The Nuclear Pore-Associated TREX-2 Complex Employs Mediator to Regulate Gene Expression.,Schneider M, Hellerschmied D, Schubert T, Amlacher S, Vinayachandran V, Reja R, Pugh BF, Clausen T, Kohler A Cell. 2015 Aug 27;162(5):1016-28. doi: 10.1016/j.cell.2015.07.059. PMID:26317468[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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