Modeling the Budding Yeast Cell Cycle

sic1∆ cdc6∆2-49 cdh1∆ GALL-CDC20

Simulation:

Change of parameters: ksc1'=ksc1"=0, ksf6'=ksf6"=ksf6"'=0, kscdh=0, ks20'=4, MDT=150, init CDH1T=CDH1=0.
Length of G1 phase: 141 min.
Mass at division: 2.2.

Experiments:

Cross, F.R. (2003). Two redundant oscillatory mechanisms in the yeast cell cycle. Dev. Cell 4:741-752.
[Abstract] [Article]
Experimental results: Supplementary information, rescued.
Comments: Cdc20 serves as the G1 stabilizer in this mutant. Because it is synthesized constitutively, Cdc20 does not disappear after mitotic exit when Clb2 is degraded. SBF and MBF turn on as usual, but Clb5 does not accumulate because it continues to be degraded by Cdc20. The cell is delayed in G1 until Clb5-kinase activity eventually triggers DNA synthesis. At that point, Cdc20 is inactivated by Mad2, allowing Clb2 to rise and drive the cell into mitosis. When [SPN] =1, the inhibition on Cdc20 is removed, and Clb2 is degraded, returning the cell to G1.