Anaphase Promoting Complex Flashcards, test questions and answers

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What is Anaphase Promoting Complex?

Anaphase Promoting Complex (APC) is a large multimeric protein complex that plays a key role in regulating progression through mitosis. It is involved in the destruction of cyclin-B, which triggers entry into anaphase and the separation of sister chromatids. The APC complex also directs movement of chromosomes to the poles and degradation of proteins associated with metaphase. Additionally, it has been linked to regulation of chromosome condensation and spindle assembly checkpoint. The APC complex is composed of nine distinct subunits which are divided into two groups: activators and inhibitors. The activator group includes Cdc20, Cdh1, Apc2, Apc4 and Apc5. These proteins interact with each other to form an active form of APC called the E3 ubiquitin ligase that marks substrates for degradation by proteosomes during mitosis. On the other hand, the inhibitor group includes Apc1, Apc3, Apc6 and Hct1 which prevent premature activation of APC activity until cyclin-B levels diminish during late mitosis. Once cyclin-B levels drop below a certain threshold then these inhibitors become inactive allowing full activation of APC activity. The importance of APC cannot be overstated as it regulates progression through mitosis so cells can divide properly without leading to birth defects or cancerous growths due to cells placing too many or too few chromosomes into daughter cells following cell division.