Spindle checkpoint protein Bub1 is required for kinetochore localization of Mad1, Mad2, Bub3, and CENP-E, independently of its kinase activity.

ABSTRACT: 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 durin

SUBMITTER: Sharp-Baker H 

PROVIDER: S-EPMC2192030 | biostudies-literature | 2001 Jun

REPOSITORIES: biostudies-literature