title: The eIF3 interactome reveals the translasome, a supercomplex linking protein synthesis and degradation machineries.
abstract: eIF3 promotes translation initiation, but relatively little is known about its full range of activities in the cell. Here, we employed affinity purification and highly sensitive LC-MS/MS to decipher the fission yeast eIF3 interactome, which was found to contain 230 proteins. eIF3 assembles into a large supercomplex, the translasome, which contains elongation factors, tRNA synthetases, 40S and 60S ribosomal proteins, chaperones, and the proteasome. eIF3 also associates with ribosome biogenesis factors and the importins-beta Kap123p and Sal3p. Our genetic data indicated that the binding to both importins-beta is essential for cell growth, and photobleaching experiments revealed a critical role for Sal3p in the nuclear import of one of the translasome constituents, the proteasome. Our data reveal the breadth of the eIF3 interactome and suggest that factors involved in translation initiation, ribosome biogenesis, translation elongation, quality control, and transport are physically linked to facilitate efficient protein synthesis.
authors.affiliation: Molecular and Cellular Biology Department, Lester and Sue Smith Breast Center, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Sha
authors.forename: Laurence M
authors.initials: LM
authors.lastname: Brill
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Cabrera
authors.forename: Oded
authors.initials: O
authors.lastname: Kleifeld
authors.forename: Judith S
authors.initials: JS
authors.lastname: Scheliga
authors.forename: Michael H
authors.initials: MH
authors.lastname: Glickman
authors.forename: Eric C
authors.initials: EC
authors.lastname: Chang
authors.forename: Dieter A
authors.initials: DA
authors.lastname: Wolf
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D021581:Active Transport, Cell Nucleus / Q000502:physiology; D004798:Enzymes / Q000378:metabolism; D039621:Eukaryotic Initiation Factor-3 / Q000378:metabolism*; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000502:physiology*; D046988:Proteasome Endopeptidase Complex / Q000502:physiology*; D014176:Protein Biosynthesis / Q000502:physiology*; D025941:Protein Interaction Mapping / Q000379:methods; D054657:Ribosome Subunits / Q000378:metabolism; D012568:Schizosaccharomyces / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000032:analysis / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D028961:beta Karyopherins / Q000378:metabolism
chemical_list: D004798:Enzymes; D039621:Eukaryotic Initiation Factor-3; D046912:Multiprotein Complexes; D029702:Schizosaccharomyces pombe Proteins; D028961:beta Karyopherins; D046988:Proteasome Endopeptidase Complex