Anaphase-promoting complex

Anaphase-promoting complex (APC) is a complex of several proteins which is activated during mitosis to initiate anaphase. The APC is a ubiquitin ligase or E3 protein that marks target proteins for degradation by the proteasome. The irreversibility of proteolysis is utilized by cells to give cell cycle directionality.

Related Topics:
Proteins - Mitosis - Anaphase - Ubiquitin ligase - Proteasome

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It indirectly triggers the degradation of cohesin, the protein complex that attaches sister chromatids to each other. This allows them to separate in the manner characteristic of anaphase. The APC also marks the mitotic cyclins for degradation. This disassembles the MPF and thereby promotes the exit from mitosis.

Related Topics:
Chromatid - Anaphase - Cyclin - MPF - Mitosis

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The activity of the APC is inhibited by the spindle checkpoint when not all kinetochores are properly attached to the mitotic spindle.

Related Topics:
Spindle checkpoint - Mitotic spindle

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There are two forms of the APC which target different sets of proteins and which are regulated differently. One, which is active early in mitosis and is responsible for triggering anaphase onset, contains Cdc20. The other, which is active later and drives exit from mitosis, contains Hct1 instead.

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It was the discovery of the APC (and SCF) and the key role that they have in eukaryotic cell reproduction that established once and for all the importance of ubiquitin-mediated proteolysis in eukaryotic cell biology. Once perceived as a system exclusively invoved in removing damaged protein from the cell, ubiquitination and subsequent protein degradation by the proteasome is now perceived as a universal regulatory mechanism for signal transduction whose importance approach protein phosphorylation.

Related Topics:
SCF - Ubiquitin - Proteasome - Signal transduction - Phosphorylation

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