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Updated: Jun 1, 2026

Monitoring Kinase and Phosphatase Activities Through the Cell Cycle by Ratiometric FRET
13:38

Monitoring Kinase and Phosphatase Activities Through the Cell Cycle by Ratiometric FRET

Published on: January 27, 2012

Greatwall kinase, ARPP-19 and protein phosphatase 2A: shifting the mitosis paradigm

Olivier Haccard1, Catherine Jessus

  • 1UMR-CNRS 7622 Biologie du Développement, Université Paris 6, 9 quai Saint-Bernard, 75005 Paris, France.

Results and Problems in Cell Differentiation
|June 2, 2011
PubMed

Insights

Scientists identified PP2A-B55δ as the key phosphatase for mitotic exit. Its activity is regulated by the Greatwall kinase, which inhibits PP2A-B55δ via ARPP-19, controlling cell division.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Mitosis entry is driven by cyclin-dependent kinase 1 (CDK1) activation.
  • Phosphorylation events during M-phase must be reversed for mitotic exit.
  • The identity and regulation of the phosphatase controlling mitotic exit remained unclear.

Purpose of the Study:

  • To identify the major phosphatase responsible for mitotic exit.
  • To elucidate the regulatory mechanism controlling this phosphatase.
  • To understand the role of this phosphatase in cell division control.

Main Methods:

  • Experiments utilizing Xenopus egg extracts.
  • Biochemical assays to determine phosphatase activity.
  • Kinase assays to study regulatory pathways.

Main Results:

  • PP2A-B55δ was identified as the primary phosphatase controlling exit from mitosis.
  • The kinase Greatwall negatively regulates PP2A-B55δ.
  • Greatwall phosphorylates ARPP-19, converting it into an inhibitor of PP2A-B55δ.

Conclusions:

  • PP2A-B55δ is the key phosphatase for mitotic exit.
  • The Greatwall-ARPP-19 pathway provides a critical regulatory mechanism for controlling mitotic exit.
  • These findings offer new insights into the precise control of cell division.

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