CRM1 is responsible for intracellular transport mediated by the nuclear export signal.
The discovery of nuclear export signals (NESs) in a number of proteins revealed the occurrence of signal-dependent transport of proteins from the nucleus to the cytoplasm. Although the consensus motif of the NESs has been shown to be a leucine-rich, short amino-acid sequence, its receptor has not been identified. A cytotoxin leptomycin B (LMB) has recently been suggested to inhibit the NES-mediated transport of Rev protein. Here we show that LMB is a potent and specific inhibitor of the NES-dependent nuclear export of proteins. Moreover, we have found a protein of relative molecular mass 110K (p110) in Xenopus oocyte extracts that binds to the intact NES but not to the mutated, non-functional NES. The binding of p110 to NES is inhibited by LMB. We show that p110 is CRM1, which is an evolutionarily conserved protein originally found as an essential nuclear protein in fission yeast and known as a likely target of LMB. We also show that nuclear export of a fission yeast protein, Dsk1, which has a leucine-rich NES, is disrupted in wild-type yeast treated with LMB or in the crm1 mutant. These results indicate that CRM1 is an essential mediator of the NES-dependent nuclear export of proteins in eukaryotic cells.
Fukuda
M
M
Department of Biophysics, Graduate School of Science, Kyoto University, Japan.
Asano
S
S
Nakamura
T
T
Adachi
M
M
Yoshida
M
M
Yanagida
M
M
Nishida
E
E
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D017124:Conserved Sequence; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006801:Humans; D028884:Karyopherins; D020929:Mitogen-Activated Protein Kinase Kinases; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces; D014981:Xenopus; D000097606:Exportin 1 Protein
D002352:Carrier Proteins; D005231:Fatty Acids, Unsaturated; D028884:Karyopherins; D020929:Mitogen-Activated Protein Kinase Kinases; D009687:Nuclear Proteins; D011494:Protein Kinases; D018160:Receptors, Cytoplasmic and Nuclear; D011993:Recombinant Fusion Proteins; D000097606:Exportin 1 Protein; C038753:leptomycin B