Cell Size at S Phase Initiation: An Emergent Property of the G1/S Network
Figure 3
Simulated Time Courses for Protein and Protein Complex Concentrations
T1 and T2 represent the threshold-overcome times. In early G1, cytoplasmic Far1, Cln3, and Cdk1 are imported into the nucleus.
(A) Nuclear Cdk1-Cln3-Far1 complex reaches its maximal value after 30 min and becomes degraded upon overcoming the Cln3/Far1 threshold (T1). Then, Cdk1-Cln3 accrues in the nucleus.
(B) At about 50 min the accumulation of active SBF/MBF reaches its half-maximal value.
(C) Cln and Clb cyclins are produced in substantial amounts.
(D) Cdk1-Cln1,2 is accumulated both in cytoplasm and nucleus.
(E–F) Cdk1-Clb5,6 accumulates preferentially in the nucleus.
(F) The half-maximal value of nuclear Cdk1-Clb5,6 is reached at around 80 min, thereby setting the value of the second threshold (T2).