title: Nucleocytoplasmic shuttling of the Rpb4p and Rpb7p subunits of Saccharomyces cerevisiae RNA polymerase II by two pathways.
abstract: Rpb4p and Rpb7p are subunits of the RNA polymerase II of Saccharomyces cerevisiae that form a dissociable heterodimeric complex. Whereas the only reported function of Rpb7p is related to transcription, Rpb4p has been found to also act in mRNA export and in the major mRNA decay pathway that operates in the cytoplasm, thus raising the possibility that Rpb4p links between the nuclear and cytoplasmic processes. Here we show that both Rpb4p and Rpb7p shuttle between the nucleus and the cytoplasm. Shuttling kinetics of the two proteins are similar as long as their interaction is possible, suggesting that they shuttle as a heterodimer. Under normal conditions, shuttling of Rpb4p and Rpb7p depends on ongoing transcription. However, during severe stresses of heat shock, ethanol, and starvation, the two proteins shuttle via a transcription-independent pathway. Thus, Rpb4p and Rpb7p shuttle via two pathways, depending on environmental conditions.
authors.affiliation: Department of Molecular Microbiology, Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel 31096.
authors.forename: Michael
authors.initials: M
authors.lastname: Selitrennik
authors.forename: Lea
authors.initials: L
authors.lastname: Duek
authors.forename: Rona
authors.initials: R
authors.lastname: Lotan
authors.forename: Mordechai
authors.initials: M
authors.lastname: Choder
mesh_terms: D021581:Active Transport, Cell Nucleus; D005800:Genes, Fungal; D018869:Heat-Shock Response; D007700:Kinetics; D008954:Models, Biological; D016296:Mutagenesis; D021122:Protein Subunits; D012319:RNA Polymerase II / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D021122:Protein Subunits; D012331:RNA, Fungal; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D012319:RNA Polymerase II