A giant nucleopore protein that binds Ran/TC4.
Ran/TC4 is a small nuclear G protein that forms a complex with the chromatin-bound guanine nucleotide release factor RCC1 (ref. 2). Loss of RCC1 causes defects in cell cycle progression, RNA export and nuclear protein import. Some of these can be suppressed by overexpression of Ran/TC4 (ref. 1), suggesting that Ran/TC4 functions downstream of RCC1. We have searched for proteins that bind Ran/TC4 by using a two-hybrid screen, and here we report the identification of RanBP2, a novel protein of 3,224 residues. This giant protein comprises an amino-terminal 700-residue leucine-rich region, four RanBP1-homologous (refs 9, 10) domains, eight zinc-finger motifs similar to those of NUP153 (refs 11, 12), and a carboxy terminus with high homology to cyclophilin. The molecule contains the XFXFG pentapeptide motif characteristic of nuclear pore complex (NPC) proteins, and immunolocalization suggests that RanBP2 is a constituent of the NPC. The fact that NLS-mediated nuclear import can be inhibited by an antibody directed against RanBP2 supports a functional role in protein import through the NPC.
Yokoyama
N
N
Department of Molecular Biology, Graduate School of Medical Science, Kyushu-University, Fukuoka, Japan.
Hayashi
N
N
Seki
T
T
Panté
N
N
Ohba
T
T
Nishii
K
K
Kuma
K
K
Hayashida
T
T
Miyata
T
T
Aebi
U
U
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli; D006367:HeLa Cells; D006801:Humans; D018832:Molecular Chaperones; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers / Q000235:genetics; D020931:ran GTP-Binding Protein
D004268:DNA-Binding Proteins; D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; C094493:ran-binding protein 2; D020931:ran GTP-Binding Protein