JCB logo
Avanti Polar Lipids, Inc.
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published online 11 June 2001. doi:10.1083/jcb.153.6.1239
This Article
Right arrow Full Text
Right arrow Full Text (PDF, 561K)
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 Sharp-Baker, H.
Right arrow Articles by Chen, R.-H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sharp-Baker, H.
Right arrow Articles by Chen, R.-H.
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, 0021-9525/2001//1239 $5.00
The Journal of Cell Biology, Volume 153, Number 6, , 2001 1239-1250

Original Article

Spindle Checkpoint Protein Bub1 Is Required for Kinetochore Localization of Mad1, Mad2, Bub3, and Cenp-E, Independently of Its Kinase Activity



Hilary Sharp-Bakera and Rey-Huei Chena

a Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853
Department of Molecular Biology and Genetics, 258 Biotechnology Bldg., Cornell University, Ithaca, NY 14583.(607) 255-6249(607) 255-6542

rc70{at}cornell.edu

The spindle checkpoint inhibits the metaphase to anaphase transition until all the chromosomes are properly attached to the mitotic spindle. We have isolated a Xenopus homologue of the spindle checkpoint component Bub1, and investigated its role in the spindle checkpoint in Xenopus egg extracts. Antibodies raised against Bub1 recognize a 150-kD phosphoprotein at both interphase and mitosis, but the molecular mass is reduced to 140 upon dephosphorylation in vitro. Bub1 is essential for the establishment and maintenance of the checkpoint and is localized to kinetochores, similar to the spindle checkpoint complex Mad1–Mad2. However, Bub1 differs from Mad1–Mad2 in that Bub1 remains on kinetochores that have attached to microtubules; the protein eventually dissociates from the kinetochore during anaphase. Immunodepletion of Bub1 abolishes the spindle checkpoint and the kinetochore binding of the checkpoint proteins Mad1, Mad2, Bub3, and CENP-E. Interestingly, reintroducing either wild-type or kinase-deficient Bub1 protein restores the checkpoint and the kinetochore localization of these proteins. Our studies demonstrate that Bub1 plays a central role in triggering the spindle checkpoint signal from the kinetochore, and that its kinase activity is not necessary for the spindle checkpoint in Xenopus egg extracts.

Key Words: spindle checkpoint • Xenopus • kinetochore • Bub1 • Mad1

© 2001 The Rockefeller University Press

Abbreviations used in this paper: APC, anaphase-promoting complex; CSF, cytostatic factor; LPC, leupeptin, pepstatin, and chymostatin; LPP, lambda protein phosphatase; MAP, mitogen-activated protein; XB, extract buffer.


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