共 40 条
Individual binding pockets of importin-β for FG-nucleoporins have different binding properties and different sensitivities to RanGTP
被引:55
作者:
Otsuka, Shotaro
[1
]
Iwasaka, Shizuka
[1
]
Yoneda, Yoshihiro
[2
]
Takeyasu, Kunio
[1
]
Yoshimura, Shige H.
[1
,3
]
机构:
[1] Kyoto Univ, Lab Plasma Membrane & Nucl Signaling, Grad Sch Biostudies, Sakyo Ku, Kyoto 6268501, Japan
[2] Osaka Univ, Grad Sch Frontier Biosci, Biomol Dynam Grp, Suita, Osaka 5650871, Japan
[3] Japan Sci & Technol Agcy, Core Res Evolut Sci & Technol, Kawaguchi, Saitama 3320012, Japan
来源:
基金:
日本科学技术振兴机构;
日本学术振兴会;
关键词:
nuclear import;
nuclear pore complex;
nuclear transport;
scanning probe microscopy;
single-molecule force measurement;
D O I:
10.1073/pnas.0802647105
中图分类号:
O [数理科学和化学];
P [天文学、地球科学];
Q [生物科学];
N [自然科学总论];
学科分类号:
07 ;
0710 ;
09 ;
摘要:
Importin-beta mediates protein transport across the nuclear envelope through the nuclear pore complex (NPC) by interacting with components of the NPC, called nucleoporins, and a small G protein, Ran. Although there is accumulated knowledge on the specific interaction between importin-beta and the Phe-Gly (FG) motif in the nucleoporins as well as the effect of RanGTIP on this interaction, the molecular mechanism by which importin-beta shuttles across the nuclear envelope through the NPC is unknown. In this study, we focused on four binding pockets of importin-beta for the FG motifs and characterized the interaction using a single-molecule force-measurement technique with atomic-force microscopy. The results from a series of importin-beta mutants containing amino acid substitutions within the FG-binding pockets demonstrate that the individual FG-binding pockets have different affinities to FG-Nups (Nup62 and Nup153) and different sensitivities to RanGTP; the binding of RanGTP to the amino-terminal domain of importin-beta induces the conformational change of the entire molecule and reduces the affinity of some of the pockets but not others. These heterogeneous characteristics of the multiple FG-binding pockets may play an important role in the behavior of importin-p within the NPC. Single-molecule force measurement using the entire molecule of an NPC from a Xenopus oocyte also implies that the reduction of the affinity by RanGTP really occurs at the nucleoplasmic side of the entire NPC.
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页码:16101 / 16106
页数:6
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