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#PP2A

2 public questions tagged with this topic.

Cell Cycle Regulation

Which phosphatase deactivates mitotic CDKs to promote exit from mitosis?

Lowering mitotic kinase activity requires collaboration between ubiquitin mediated cyclin destruction and phosphatase mediated substrate dephosphorylation. APC/C-Cdc20 degrades cyclin B reducing CDK1 catalytic availability, but hundreds of phosphorylated residues remain. Phosphatases execute erasure. In yeast, Cdc14 is dominant enzyme preferentially dephosphorylating proline-directed CDK sites, including Cdh1 to activate APC/C-Cdh1 for further cyclin clearance, Swi5 for Sic1 transcription and structural cytokinesis proteins. In metazoa, PP2A-B55 family is major mitotic exit phosphatase regulat

Ref: Wurzenberger & Gerlich, Mitotic Phosphatases PP2A and Cdc14 in Exit, J Cell Biol 2011; NCBI Bookshelf, Regulation of Mitotic Exit.

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Cell Cycle Regulation

Which factor regulates the exit from mitosis?

Finishing mitosis demands comprehensive reversal of CDK1 mediated phosphorylations and elimination of cyclin B activity. Cdc14 family phosphatases coordinate this program. In budding yeast, Cdc14 resides sequestered in nucleolus bound to inhibitor Net1 also called Cfi1. Mitotic entry maintains sequestration via high CDK activity. In early anaphase, FEAR pathway comprising separase, Slk19 homodimer, Spo12, Zds1 and Zds2 induces transient release. Subsequently Mitotic Exit Network MEN, Hippo-like cascade of Tem1 GTPase localized at daughter spindle pole body, polo kinase Cdc15 and Dbf2-Mob1 comp

Ref: Stegmeier & Amon, Closing Mitosis: Regulation of Cdc14 Phosphatase, Annu Rev Genet 2004; Bardin & Amon, MEN and Mitotic Exit.

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