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A more recent version of this article appeared on June 1, 2004
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Submitted on February 12, 2004
Revised on March 12, 2004
Accepted on March 12, 2004
1 Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
* Corresponding author. E-mail address: tktang{at}ibms.sinica.edu.tw.
We have previously identified a new centrosomal protein, CPAP (centrosomal protein 4.1-associated protein), which is associated with the
-tubulin complex. Here we report that CPAP carries a novel microtubule-destabilizing motif (MDM) that not only inhibits microtubule nucleation from the centrosome but also depolymerizes taxol-stabilized microtubules. Deletion mapping and functional analyses have defined a 112-residue CPAP which is necessary and sufficient for microtubule destabilization. This 112-residue CPAP directly recognizes the plus end of a microtubule and inhibits microtubule nucleation from the centrosome. Biochemical and functional analyses revealed that this 112-residue CPAP also binds to tubulin dimers resulting in the destabilization of microtubules. Using the tetracycline-controlled system (tet-off), we observed that overexpression of this 112-residue CPAP inhibits cell proliferation and induces apoptosis after G2/M arrest. The possible mechanisms of how this 112-residue motif in CPAP that inhibits MT nucleation from the centrosome and disassembles preformed MTs are discussed.