JCB logo
Quantitative Colocalization Analysis Software
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 563K)
Right arrow PPT slides of all figures
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kose, S.
Right arrow Articles by Yoneda, Y.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kose, S.
Right arrow Articles by Yoneda, Y.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Facebook   Add to Reddit   Add to Technorati   Add to Twitter  
What's this?

© The Rockefeller University Press, 0021-9525/1997//841 $5.00
The Journal of Cell Biology, Volume 139, Number 4, , 1997 841-849

Article

Ran-unassisted Nuclear Migration of a 97-kD Component of Nuclear Pore–targeting Complex



Shingo Kose, Naoko Imamoto, Taro Tachibana, Takuya Shimamoto, and Yoshihiro Yoneda

Department of Anatomy and Cell Biology, Osaka University Medical School, Suita, Osaka 565, Japan

A 97-kD component of nuclear pore-targeting complex (the β-subunit of nuclear pore–targeting complex [PTAC]/importin/karyopherin) mediates the import of nuclear localization signal (NLS)-containing proteins by anchoring the NLS receptor protein (the {alpha}-subunit of PTAC/importin/karyopherin) to the nuclear pore complex (NPC). The import requires a small GTPase Ran, which interacts directly with the β-subunit. The present study describes an examination of the behavior of the β-subunit in living cells and in digitonin-permeabilized cells. In living cells, cytoplasmically injected β-subunit rapidly migrates into the nucleus. The use of deletion mutants reveals that nuclear migration of the β-subunit requires neither Ran- nor {alpha}-subunit–binding but only the NPC-binding domain of this molecule, which is also involved in NLS-mediated import. Furthermore, unlike NLS-mediated import, a dominant-negative Ran, defective in GTP-hydrolysis, did not inhibit nuclear migration of the β-subunit. In the digitonin-permeabilized cell-free import assay, the β-subunit transits rapidly through the NPC into the nucleus in a saturating manner in the absence of exogenous addition of soluble factors. These results show that the β-subunit undergoes translocation at the NPC in a Ran-unassisted manner when it does not carry {alpha}-subunit/NLS substrate. Therefore, a requirement for Ran arises only when the β-subunit undergoes a translocation reaction together with the {alpha}-subunit/NLS substrate. The results provide an insight to the yet unsolved question regarding the mechanism by which proteins are directionally transported through the NPC, and the role of Ran in this process.

Abbreviations used in this paper: GFP, green fluorescent protein: GST, glutathione-S-transferase; MDBK, Madin-Darby bovine kidney; NLS, nuclear localization signal; NPC, nuclear pore complex; PTAC, nuclear pore–targeting complex.

S. Kose and N. Imamoto contributed equally to this work.

Address all correspondence to Yoshihiro Yoneda, Department of Anatomy and Cell Biology, Osaka University Medical School, 2-2 Yamada-oka, Suita, Osaka 565, Japan. Tel.: (81) 6 879 3211. Fax: (81) 6 879 3219.

Takuya Shimamoto's present address is Department of Microbiology, Osaka University Medical School, Suita, Osaka 565, Japan.


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Facebook Facebook   Add to Reddit Reddit   Add to Technorati Technorati   Add to Twitter Twitter    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents