Related Experiment Video
Updated: May 5, 2026

Reconstitution of Cell-cycle Oscillations in Microemulsions of Cell-free Xenopus Egg Extracts
Published on: September 27, 2018
Role for regulated phosphatase activity in generating mitotic oscillations in Xenopus cell-free extracts
Tongli Zhang1, John J Tyson, Béla Novák
1Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom.
Abstract:
Although current textbook explanations of cell-cycle control in eukaryotes emphasize the periodic activation of cyclin-dependent protein kinases (CDKs), recent experimental observations suggest a significant role for the periodic activation and inactivation of a CDK-counteracting protein phosphatase 2A with a B55δ subunit (PP2A:B55δ), during mitotic cycles in frog-egg extracts and early embryos. In this paper, we extend an earlier mathematical model of embryonic cell cycles to include experimentally motivated roles for PP2A:B55δ and its regulation by Greatwall kinase. Our model is consistent with what is already known about the regulation of CDK and PP2A:B55δ in frog eggs, and it suggests a previously undescribed role for the Greatwall-PP2A:B55δ interaction in creating a toggle switch for activation of the anaphase-promoting complex as embryonic cells exit mitosis and return to interphase.
More Related Videos
Related Concept Videos
Positive Regulator Molecules
Positive Regulator Molecules
M-Cdk Drives Transition Into Mitosis
Cyclin-dependent kinases, or Cdks, work in concert with cyclins to control cell cycle transitions. M-Cdk, a complex of Cdk1 bound to M cyclin, is a well-known example of this coordinated control that drives the transition from the G2 to the M phase.
M cyclin...
Anaphase Promoting Complex
Negative Regulator Molecules
Protein Kinases and Phosphatases
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...

