Regulation
The APCCdc20 complex regulates itself so that it is present during the appropriate times of the cell cycle. In order for Cdc20 to bind the APC, specific APC subunits must be phosphorylated by Cdk1 (among other Cdks). Therefore, when cdk activity is high in mitosis, and the cell must prepare to enter anaphase and exit mitosis, the APCCdc20 complex is activated. Once active, APCCdc20 promotes the degradation of Cdks by inactivating S/M cyclins. Cdk degradation brings about lower rates of APC phosphorylation and thus lower rates of Cdc20 binding. In this way, the APCCdc20 complex inactivates itself by the end of mitosis. However, because the cell does not immediately enter the cell cycle, Cdks can not immediately be reactivated. Multiple different mechanisms inhibit Cdks in G1: Cdk inhibitor proteins are expressed, and cyclin gene expression is down-regulated. Importantly, cyclin accumulation is also prevented by Cdh1.
Read more about this topic: CDC20
Famous quotes containing the word regulation:
“Nothing can be more real, or concern us more, than our own sentiments of pleasure and uneasiness; and if these be favourable to virtue and unfavourable to vice, no more can be requisite to the regulation of our conduct and behavior.”
—David Hume (1711–1776)
“Lots of white people think black people are stupid. They are stupid themselves for thinking so, but regulation will not make them smarter.”
—Stephen Carter (b. 1954)
“Nothing changes my twenty-six years in the military. I continue to love it and everything it stands for and everything I was able to accomplish in it. To put up a wall against the military because of one regulation would be doing the same thing that the regulation does in terms of negating people.”
—Margarethe Cammermeyer (b. 1942)