Investigating the function and regulation of UbcH10-APC/C

The Anaphase-Promoting Complex/Cyclosome (APC/C) is an E3 ubiquitin ligase that, through targeting protein substrates for polyubiquitylation and 26S proteasome-mediated degradation coordinates the progression of cells through mitosis and the successive G1 phase of the cell-cycle. APC/C E3 ligase activity is stimulated, in the presence of the E2-ubiquitin conjugating enzymes UbcH10 and Ube2S, by the temporally coordinated recruitment of one of two related activator proteins, Cdc20 or Cdh1, to the APC/C; Cdc20 and Cdh1 also serve in conjunction with particular APC/C subunits to bind substrates. Published work from our laboratory has previously determined that the ubiquitin ligase activity of the APC/C is regulated by the transcriptional co-activators CBP and p300. We have also determined that the DNA damage response, and scaffold protein, MDC1 regulates APC/C-Cdc20 activity during mitosis by promoting Cdc20 association with the APC/C, whilst the transcriptional repressor, TIF1y, also regulates APC/C-Cdc20 activity in mitosis. We have also established that the DDR protein, 53BP1, is both an inhibitor, and substrate of the APC/C, and regulates entry into, and progression through, mitosis. To further our understanding of APC/C function we have recently characterized the interactome of the APC/C E2-conjugating enzyme, UbcH10. The current project will investigate the ability of UbcH10-interacting proteins to modulate UbcH10-APC/C activity and function.