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J Cell Biol April 11, 2005; 169 (1): 61-71.
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Inhibition of the anaphase-promoting complex by the Xnf7 ubiquitin ligase.

Casaletto JB , Nutt LK , Wu Q , Moore JD , Etkin LD , Jackson PK , Hunt T , Kornbluth S .

Degradation of specific protein substrates by the anaphase-promoting complex/cyclosome (APC) is critical for mitotic exit. We have identified the protein Xenopus nuclear factor 7 (Xnf7) as a novel APC inhibitor able to regulate the timing of exit from mitosis. Immunodepletion of Xnf7 from Xenopus laevis egg extracts accelerated the degradation of APC substrates cyclin B1, cyclin B2, and securin upon release from cytostatic factor arrest, whereas excess Xnf7 inhibited APC activity. Interestingly, Xnf7 exhibited intrinsic ubiquitin ligase activity, and this activity was required for APC inhibition. Unlike other reported APC inhibitors, Xnf7 did not associate with Cdc20, but rather bound directly to core subunits of the APC. Furthermore, Xnf7 was required for spindle assembly checkpoint function in egg extracts. These data suggest that Xnf7 is an APC inhibitor able to link spindle status to the APC through direct association with APC core components.

PubMed ID: 15824132
PMC ID: PMC2171901
Article link: J Cell Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: ccnb1 ccnb1.2 ccnb2 cdc20 cdc27 fbxo5 mbp ube2d1 xnf7

Article Images: [+] show captions
References [+] :
Acquaviva, The anaphase promoting complex/cyclosome is recruited to centromeres by the spindle assembly checkpoint. 2004, Pubmed