Isolation of a protein that is essential for the first step of nuclear protein import.
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.
Görlich
D
D
Wellcome/CRC Institute, Cambridge, England.
Prehn
S
S
Laskey
R A
RA
Hartmann
E
E
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport / Q000187:drug effects; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000378:metabolism*; D003001:Cloning, Molecular; D003600:Cytosol / Q000737:chemistry* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics; D006367:HeLa Cells; D006651:Histocytochemistry; D006801:Humans; D028884:Karyopherins; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010063:Ovum; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014981:Xenopus; D028901:alpha Karyopherins
D018076:DNA, Complementary; D028884:Karyopherins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D028901:alpha Karyopherins; D000255:Adenosine Triphosphate