The GTP-binding protein Ran/TC4 is required for protein import into the nucleus

Nature. 1993 Oct 14;365(6447):661-3. doi: 10.1038/365661a0.


Two cytosolic fractions (A and B) from Xenopus oocytes are sufficient to support protein import into the nuclei of digitonin-permeabilized cells. Fraction A recognizes the nuclear localization sequence (NLS) and binds the import substrate to the nuclear envelope, whereas fraction B mediates the subsequent passage of the bound substrate into the nucleus. Here we report that two interacting components are required for full fraction-B activity, purify one of these components to homogeneity, and show that it is the highly abundant GTP-binding protein Ran (Ras-related nuclear protein)/TC4.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Transport
  • Cell Nucleus / metabolism*
  • Cytosol / metabolism
  • GTP-Binding Proteins / metabolism*
  • Guanine Nucleotides / metabolism
  • HeLa Cells
  • Humans
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Nuclear Proteins / metabolism*
  • Oocytes
  • Proteins / metabolism
  • Rats
  • Rats, Inbred BUF
  • Recombinant Proteins / metabolism
  • Xenopus
  • ran GTP-Binding Protein


  • Guanine Nucleotides
  • Nuclear Proteins
  • Proteins
  • Recombinant Proteins
  • GTP-Binding Proteins
  • ran GTP-Binding Protein