title: Mad2-Independent inhibition of APCCdc20 by the mitotic checkpoint protein BubR1.
abstract: The mitotic checkpoint blocks the activation of the anaphase-promoting complex (APC) until all sister chromatids have achieved bipolar attachment to the spindle. A checkpoint complex containing BubR1 and Bub3 has been purified from mitotic human cells. Upon checkpoint activation, the BubR1-Bub3 complex interacts with Cdc20. In the absence of Mad2, BubR1 inhibits the activity of APC by blocking the binding of Cdc20 to APC. Surprisingly, the kinase activity of BubR1 is not required for the inhibition of APCCdc20. BubR1 also prevents the activation of APCCdc20 in Xenopus egg extracts, and restores the mitotic arrest in Cdc20-overexpressing cells treated with nocodazole. Because BubR1 also interacts with the mitotic motor CENP-E, the ability of BubR1 to inhibit APC may be regulated by kinetochore tension or occupancy.
authors.affiliation: Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 75390, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Tang
authors.forename: R
authors.initials: R
authors.lastname: Bharadwaj
authors.forename: B
authors.initials: B
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Yu
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism* / Q000502:physiology*; D002352:Carrier Proteins; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005656:Fungal Proteins / Q000378:metabolism* / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007313:Insecta; D064246:Mad2 Proteins; D008938:Mitosis; D008954:Models, Biological; D009687:Nuclear Proteins; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism* / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism; D014981:Xenopus
chemical_list: C577495:CDC20 protein, S cerevisiae; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; C577695:MAD2 protein, S cerevisiae; D064246:Mad2 Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D011494:Protein Kinases; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases