title: A distinct nuclear import pathway used by ribosomal proteins.
abstract: Protein transport into the nucleus is governed by the interaction of soluble transport factors with their import substrates and nuclear pore complexes. Here, we identify a major distinct nuclear import pathway, mediated by a previously uncharacterized yeast beta karyopherin Kap123p. The predominant substrates for this pathway are ribosomal proteins, which must be imported into the nucleus prior to assembly into pre-ribosomes. Kap123p binds directly to its transport substrates, repeat motif-containing nucleoporins, and Ran-GTP. We show that the related protein Pse1p is also a karyopherin and can functionally substitute for Kap123p; both are capable of specifically directing a ribosomal nuclear localization signal reporter to the nucleus in vivo.
authors.affiliation: Laboratory of Cell Biology, Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10021, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Rout
authors.forename: G
authors.initials: G
authors.lastname: Blobel
authors.forename: J D
authors.initials: JD
authors.lastname: Aitchison
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002467:Cell Nucleus / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D012269:Ribosomal Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D028961:beta Karyopherins
chemical_list: D005656:Fungal Proteins; D009687:Nuclear Proteins; D012269:Ribosomal Proteins; D028961:beta Karyopherins