Nucleocytoplasmic transport: Ran, beta and beyond

Trends Cell Biol. 2001 Dec;11(12):497-503. doi: 10.1016/s0962-8924(01)02144-4.


Proteins, RNAs and even large macromolecular complexes are transported into and out of nuclei with remarkable rapidity and specificity. Nucleocytoplasmic transport must therefore be efficient and selective. Characterization of the roles of the importin beta family of transport receptors and of the Ran GTPase has showed how these characteristics can be achieved, but there are many examples of nucleocytoplasmic transport that do not fit this model. Here, we discuss current understanding of various transport mechanisms and evaluate cases in which the molecules and mechanisms underlying nucleocytoplasmic transport are used to carry out important cellular functions in the absence of a nucleus.

Publication types

  • Review

MeSH terms

  • Active Transport, Cell Nucleus / physiology
  • Animals
  • Cell Nucleus / metabolism*
  • Chromosomes / metabolism
  • Cytoplasm / metabolism*
  • Humans
  • Nuclear Proteins / metabolism*
  • Nucleocytoplasmic Transport Proteins*
  • RNA-Binding Proteins / metabolism*
  • Ribosomal Proteins / metabolism
  • Ribosomes / metabolism
  • Transcription Factors / metabolism
  • beta Karyopherins / metabolism*
  • ran GTP-Binding Protein / metabolism*


  • ALYREF protein, human
  • NXF1 protein, human
  • Nuclear Proteins
  • Nucleocytoplasmic Transport Proteins
  • RNA-Binding Proteins
  • Ribosomal Proteins
  • Transcription Factors
  • beta Karyopherins
  • ran GTP-Binding Protein