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Explaining the oligomerization properties of the spindle assembly checkpoint protein Mad2

Lookup NU author(s): Professor Mary Herbert


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Mad2 is an essential component of the spindle assembly checkpoint (SAC), a molecular device designed to coordinate anaphase onset with the completion of chromosome attachment to the spindle. Capture of chromosome by microtubules occur on protein scaffolds known as kinetochores. The SAC proteins are recruited to kinetochores in prometaphase where they generate a signal that halts anaphase until all sister chromatid pairs are bipolarly oriented. Mad2 is a subunit of the mitotic checkpoint complex, which is regarded as the effector of the spindle checkpoint. Its function is the sequestration of Cdc20, a protein required for progression into anaphase. The function of Mad2 in the checkpoint correlates with a dramatic conformational rearrangement of the Mad2 protein. Mad2 adopts a closed conformation (C-Mad2) when bound to Cdc20, and an open conformation (O-Mad2) when unbound to this ligand. Checkpoint activation promotes the conversion of O-Mad2 to Cdc20-bound C-Mad2. We show that this conversion requires a C-Mad2 template and we identify this in Mad1-bound Mad2. In our proposition, Mad1-bound C-Mad2 recruits O-Mad2 to kinetochores, stimulating Cdc20 capture, implying that O-Mad2 and C-Mad2 form dimers. We discuss Mad2 oligomerization and link our discoveries to previous observations related to Mad2 oligomerization. © 2005 The Royal Society.

Publication metadata

Author(s): DeAntoni A, Sala V, Musacchio A, Herbert M, Heriche J-K, Mitchison T

Publication type: Article

Publication status: Published

Journal: Philosophical Transactions of the Royal Society B: Biological Sciences

Year: 2005

Volume: 360

Issue: 1455

Pages: 637-648

ISSN (print): 0962-8436

ISSN (electronic): 1471-2970

Publisher: The Royal Society Publishing


DOI: 10.1098/rstb.2004.1618

PubMed id: 15897186


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