spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Bertinato, J.
Right arrow Articles by Hache, R. J.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Bertinato, J.
Right arrow Articles by Hache, R. J.

Journal of Cell Science, Vol 114, Issue 1 89-99, Copyright © 2001 by Company of Biologists

JOURNAL ARTICLES

Nuclear localization of Ku antigen is promoted independently by basic motifs in the Ku70 and Ku80 subunits

J Bertinato, C Schild-Poulter and RJ Hache
Graduate Program in Biochemistry, Department of Medicine, University of Ottawa, Ontario, Canada, K1Y 4K9.

The Ku antigen is a heteromeric (Ku70/Ku80), mostly nuclear protein. Ku participates in multiple nuclear processes from DNA repair to V(D)J recombination to telomere maintenance to transcriptional regulation and serves as a DNA binding subunit and allosteric regulator of DNA-dependent protein kinase. While some evidence suggests that subcellular localization of Ku may be subject to regulation, how Ku gains access to the nucleus is poorly understood. In this work, using a combination of indirect immunofluorescence and direct fluorescence, we have demonstrated that transfer of the Ku heterodimer to the nucleus is determined by basic nuclear localization signals in each of the Ku subunits that function independently. A bipartite basic nuclear localization signal between amino acids 539-556 of Ku70 was observed to be required for nuclear import of full-length Ku70 monomer, while a short Ku80 motif of four amino acids from 565-568 containing three lysines was required for the nuclear import of full-length Ku80. Ku heterodimers containing only one nuclear localization signal accumulated in the nucleus as efficiently as wild-type Ku, while site directed mutagenesis inactivating the basic motifs in each subunit, resulted in a Ku heterodimer that was completely localized to the cytoplasm. Lastly, our results indicate that mutations in Ku previously proposed to abrogate Ku70/Ku80 heterodimerization, markedly reduced the accumulation of Ku70 without affecting heterodimer formation in mammalian cells.


This article has been cited by other articles:


Home page
 J BiochemHome page
M. Kato, T. Nonaka, and S. Imajoh-Ohmi
Cleavage at the Carboxyl-Terminus of Ku80 during Apoptosis in Human Jurkat T Cells
J. Biochem., June 1, 2005; 137(6): 685 - 692.
[Abstract] [Full Text] [PDF]

Home page
 Nucleic Acids ResHome page
C. J. Janzen, F. Lander, O. Dreesen, and G. A. M. Cross
Telomere length regulation and transcriptional silencing in KU80-deficient Trypanosoma brucei
Nucleic Acids Res., December 15, 2004; 32(22): 6575 - 6584.
[Abstract] [Full Text] [PDF]


© The Company of Biologists Ltd 2001