CDC20 - Interactions

Interactions

CDC20 has been shown to interact with:

• ANAPC7
• BUB1B,
• CDC16,
• CDC27,
• Cyclin A1,
• FBXO5,
• HDAC1,
• HDAC2, and
• MAD2L1.

However, the most important interaction of Cdc20 is with the Anaphase Promoting Complex. The APC is a large E3 ubiquitin ligase, which triggers the metaphase to anaphase transition by marking select proteins for degradation. The two main targets of the APC are the S/M cyclins and the protein securin. S/M cyclins activate cyclin-dependent kinases (Cdks), which have a vast array of downstream effects that work to guide the cell through mitosis. They must be degraded for cells to exit mitosis. Securin is a protein that inhibits separase, which in turn inhibits cohesin, a protein that holds sister chromatids together. Therefore, in order for anaphase to progress, securin must be inhibited so that cohesin can be cleaved by separase. These processes are dependent on both the APC and Cdc20: When Cdks phosphorylate the APC, Cdc20 can bind and activate it, allowing both the degradation of Cdks and the cleavage of cohesin. APC activity is dependent on Cdc20 (and Cdh1), because Cdc20 often binds the APC substrates directly. In fact, it is thought that Cdc20 and Cdh1 (see below) are receptors for the KEN-box and D-box motifs on substrates. However, these sequences are normally not sufficient for ubiquitination and degradation; much remains to be learned about how Cdc20 binds its substrate.