A quantitative model for the cdc2 control of S phase and mitosis in fission yeast

Trends Genet. 1996 Sep;12(9):345-50.


In this article we consider the role of the cyclin-dependent protein kinase cdc2 in regulating progression through the fission yeast cell cycle. The onset of mitosis is governed by cdc2 in partnership with the B-type cyclin, cdc13. Recent evidence shows that the cdc2-cdc13 complex can also control the onset of S phase and, in addition, ensures that there is only one S phase per cell cycle. This leads us to propose a novel quantitative model in which different levels of cdc2 activity regulate cell-cycle progression: S phase is initiated when protein kinase activity increases from a very low to a moderate level; maintenance of this moderate level prevents re-initiation of S phase, and a further increase of activity to a high level initiates mitosis. Inactivation of the kinase activity at the end of mitosis resets the cell for a new cell cycle.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Biological Evolution
  • CDC2 Protein Kinase / genetics*
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle / genetics
  • Cyclin B
  • Cyclins
  • Drosophila / genetics
  • Drosophila Proteins
  • G1 Phase / genetics
  • G2 Phase / genetics
  • Gene Expression Regulation, Fungal
  • Mitosis*
  • Models, Biological
  • S Phase / genetics*
  • Xenopus / genetics
  • Yeasts / genetics*


  • CycB protein, Drosophila
  • Cyclin B
  • Cyclins
  • Drosophila Proteins
  • CDC2 Protein Kinase