A distinct nuclear import pathway used by ribosomal proteins

Cell. 1997 May 30;89(5):715-25. doi: 10.1016/s0092-8674(00)80254-8.


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.

MeSH terms

  • Amino Acid Sequence
  • Biological Transport
  • Cell Nucleus / metabolism
  • Fungal Proteins / metabolism
  • Molecular Sequence Data
  • Nuclear Proteins / metabolism*
  • Ribosomal Proteins / metabolism*
  • Saccharomyces cerevisiae
  • Sequence Alignment
  • beta Karyopherins


  • Fungal Proteins
  • Nuclear Proteins
  • Ribosomal Proteins
  • beta Karyopherins