title: Nuclear export of ribosomal subunits.
abstract: The partitioning of cells by a nuclear envelope ensures that precursors of ribosomes do not interact prematurely with other components of the translation machinery. Ribosomal subunits are assembled in nucleoli and exported to the cytoplasm in a CRM1/Ran-GTP-dependent fashion. Export of the large (60S) subunit requires a shuttling adaptor protein, NMD3, which binds to mature, correctly folded subunits. Immature or defective particles do not bind NMD3 and thus are excluded from the export pathway. This structural proofreading is extended into the cytoplasm, where it is believed that several energy-requiring steps release shuttling factors from the subunit, allowing it to function in translation.
authors.affiliation: Section of Molecular Genetics and Microbiology and Institute for Cellular and Molecular Biology, University of Texas at Austin, 78712, USA. arlen@mail.utexas.edu
authors.forename: Arlen W
authors.initials: AW
authors.lastname: Johnson
authors.forename: Elsebet
authors.initials: E
authors.lastname: Lund
authors.forename: James
authors.initials: J
authors.lastname: Dahlberg
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism*; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D028884:Karyopherins / Q000378:metabolism; D009154:Mutation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein / Q000378:metabolism; D000097606:Exportin 1 Protein
chemical_list: D005656:Fungal Proteins; D028884:Karyopherins; D021122:Protein Subunits; D016601:RNA-Binding Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D029701:Saccharomyces cerevisiae Proteins; D020931:ran GTP-Binding Protein; D000097606:Exportin 1 Protein; C117894:NMD3 protein, S cerevisiae