Which protein deactivates mitotic CDKs during mitotic exit?
Mitotic exit requires not only destruction of cyclin B but comprehensive reversal of CDK1-Cyclin B phosphorylation on hundreds of substrates. Specialized phosphatases execute this program. In budding yeast, Cdc14 is the master phosphatase. Most of the cell cycle it is sequestered in nucleolus bound to inhibitor Net1 or Cfi1. Two release pathways operate sequentially: the Cdc Fourteen Early Anaphase Release pathway involving separase, Slk19, Spo12 and Zds1/Zds2 provides transient liberation in early anaphase, while the Mitotic Exit Network composed of Tem1, Cdc15 and Dbf2-Mob1 kinases sustains
Ref: Stegmeier & Amon, Closing Mitosis: Role of Cdc14 Phosphatases, Annu Rev Genet 2004; Alberts et al., Chapter 17, Mitotic Exit Control.