The nuclear pore-targeting complex binds to nuclear pores after association with a karyophile.
We recently showed that a karyophilic protein forms a stable complex, termed nuclear pore-targeting complex (PTAC), with cytoplasmic components prior to nuclear pore-binding. In this study, we cloned a cDNA encoding a 97 kDa of PTAC (PTAC97). Recombinant PTAC97 completely reconstitutes the nuclear binding-step in conjunction with a 58 kDa component of PTAC (PTAC58) in the semi-intact cell-free transport assay. Biochemical analysis reveals that PTAC58 binds to a karyophilic protein, and PTAC97 is associated with PTAC58 in a 1:1 molar ratio. A complex of PTAC97 and PTAC58 targets nuclear pores, depending on the presence of a karyophile. These in vitro results suggest that the first step in nuclear import occurs through the targeting-complex formation of a karyophile with PTAC58 bound to PTAC97.
Imamoto
N
N
Department of Anatomy and Cell Biology, Osaka University Medical School, Japan.
Shimamoto
T
T
Kose
S
S
Takao
T
T
Tachibana
T
T
Matsubae
M
M
Sekimoto
T
T
Shimonishi
Y
Y
Yoneda
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D051379:Mice; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D028901:alpha Karyopherins; D028961:beta Karyopherins
D018076:DNA, Complementary; C490631:Kpna2 protein, mouse; C094999:Kpnb1 protein, mouse; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D028901:alpha Karyopherins; D028961:beta Karyopherins