A quantitative model for the cdc2 control of S phase and mitosis in fission yeast.
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.
Stern
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B
Cell Cycle Laboratory, Imperial Cancer Research Fund, London, UK. stern@icrf.icnet.uk
Nurse
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P
D000818:Animals; D005075:Biological Evolution; D016203:CDC2 Protein Kinase / Q000235:genetics* / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics; D019926:Cyclin B; D016213:Cyclins; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins; D016193:G1 Phase / Q000235:genetics; D016195:G2 Phase / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D008938:Mitosis; D008954:Models, Biological; D016196:S Phase / Q000235:genetics*; D014981:Xenopus / Q000235:genetics; D015003:Yeasts / Q000235:genetics*
C503698:CycB protein, Drosophila; D019926:Cyclin B; D016213:Cyclins; D029721:Drosophila Proteins; D016203:CDC2 Protein Kinase