Function
The APC/C's main function is to trigger the transition from metaphase to anaphase by tagging specific proteins for degradation. The two proteins of most importance that get degraded in this process as substrates of the APC/C are securin and S and M cyclins. Securin releases separase, a protease, after being degraded which in turn triggers the cleavage of cohesin, the protein complex that binds sister chromatids together. During metaphase, sister chromatids are linked by intact cohesin complexes. When securin undergoes ubiquitination by the APC/C and releases separase, which degrades cohesin, sister chromatids become free to move to opposite poles for anaphase. The APC/C also targets the mitotic cyclins for degradation, resulting in the inactivation of M-CdK (mitotic cyclin-dependent kinase) complexes, promoting exit from mitosis and cytokinesis.
Unlike the SCF, activator subunits control the APC/C. Cdc20 and Cdh1 are the two activators of particular importance to the cell cycle. These proteins target the APC/C to specific sets of substrates at different times in the cell cycle, thus driving it forward. The APC/C also plays an integral role in maintenance of chromatin metabolism, particularly in G1 and G0, and plays a key role in phosphorylation of H3 through destruction of the aurora A kinase.
Read more about this topic: Anaphase-promoting Complex
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