Literature search services are currently unavailable. During our hosting provider's UPS upgrade we experienced a hardware failure and are currently working to resolve the issue.

Preparing your results

Our searching services are busy right now. Your search will reload in five seconds.

Forgot Password

If you have forgotten your password you can enter your email here and get a temporary password sent to your email.

A role for Cdc2- and PP2A-mediated regulation of Emi2 in the maintenance of CSF arrest.

BACKGROUND: Vertebrate oocytes are arrested in metaphase II of meiosis prior to fertilization by cytostatic factor (CSF). CSF enforces a cell-cycle arrest by inhibiting the anaphase-promoting complex (APC), an E3 ubiquitin ligase that targets Cyclin B for degradation. Although Cyclin B synthesis is ongoing during CSF arrest, constant Cyclin B levels are maintained. To achieve this, oocytes allow continuous slow Cyclin B degradation, without eliminating the bulk of Cyclin B, which would induce release from CSF arrest. However, the mechanism that controls this continuous degradation is not understood. RESULTS: We report here the molecular details of a negative feedback loop wherein Cyclin B promotes its own destruction through Cdc2/Cyclin B-mediated phosphorylation and inhibition of the APC inhibitor Emi2. Emi2 bound to the core APC, and this binding was disrupted by Cdc2/Cyclin B, without affecting Emi2 protein stability. Cdc2-mediated phosphorylation of Emi2 was antagonized by PP2A, which could bind to Emi2 and promote Emi2-APC interactions. CONCLUSIONS: Constant Cyclin B levels are maintained during a CSF arrest through the regulation of Emi2 activity. A balance between Cdc2 and PP2A controls Emi2 phosphorylation, which in turn controls the ability of Emi2 to bind to and inhibit the APC. This balance allows proper maintenance of Cyclin B levels and Cdc2 kinase activity during CSF arrest.

Pubmed ID: 17276914


  • Wu Q
  • Guo Y
  • Yamada A
  • Perry JA
  • Wang MZ
  • Araki M
  • Freel CD
  • Tung JJ
  • Tang W
  • Margolis SS
  • Jackson PK
  • Yamano H
  • Asano M
  • Kornbluth S


Current biology : CB

Publication Data

February 6, 2007

Associated Grants

  • Agency: NIGMS NIH HHS, Id: R01 GM064348-02
  • Agency: NIGMS NIH HHS, Id: R01 GM067225
  • Agency: NIGMS NIH HHS, Id: R01 GM067225-05
  • Agency: NIGMS NIH HHS, Id: R01 GM64348
  • Agency: NIGMS NIH HHS, Id: R01 GM67225

Mesh Terms

  • Anaphase-Promoting Complex-Cyclosome
  • Animals
  • CDC2 Protein Kinase
  • Cdc20 Proteins
  • Cell Cycle Proteins
  • Cyclin B
  • DNA, Complementary
  • Enzyme Inhibitors
  • F-Box Proteins
  • Gene Library
  • Humans
  • Meiosis
  • Okadaic Acid
  • Oocytes
  • Phosphoprotein Phosphatases
  • Phosphorylation
  • Protein Binding
  • Proto-Oncogene Proteins c-mos
  • Recombinant Fusion Proteins
  • Ubiquitin-Protein Ligase Complexes
  • Xenopus
  • Xenopus Proteins