Isolation of a Protein That Is Essential for the First Step of Nuclear Protein Import

Cell. 1994 Dec 2;79(5):767-78. doi: 10.1016/0092-8674(94)90067-1.

Abstract

We have purified a cytosolic protein from Xenopus eggs that is essential for selective protein import into the cell nucleus. The purified protein, named importin, promotes signal-dependent binding of karyophilic proteins to the nuclear envelope. We have cloned, sequenced, and expressed a corresponding cDNA. Importin shows 44% sequence identity with SRP1p, a protein associated with the yeast nuclear pore complex. Complete, signal-dependent import into HeLa nuclei can be reconstituted by combining importin purified from Xenopus eggs or expressed in E. coli with Ran/TC4. Evidence for additional stimulatory factors is provided.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Biological Transport / drug effects
  • Cell Compartmentation*
  • Cell Nucleus / metabolism*
  • Cloning, Molecular
  • Cytosol / chemistry*
  • Cytosol / metabolism
  • DNA, Complementary / genetics
  • HeLa Cells
  • Histocytochemistry
  • Humans
  • Karyopherins
  • Molecular Sequence Data
  • Nuclear Envelope / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Ovum
  • Protein Binding
  • Recombinant Proteins / metabolism
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Sequence Homology, Nucleic Acid
  • Xenopus
  • alpha Karyopherins

Substances

  • DNA, Complementary
  • Karyopherins
  • Nuclear Proteins
  • Recombinant Proteins
  • alpha Karyopherins
  • Adenosine Triphosphate

Associated data

  • GENBANK/L36339
  • GENBANK/L36340