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Cyclin Turnover

The controlled degradation of cyclins, a key mechanism for regulating CDK activity and ensuring proper cell cycle timing.
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The statement of the theorem

Consider the concentration of a specific cyclin, [C](t)[C](t). Its degradation is catalyzed by the Anaphase Promoting Complex/Cyclosome (APC/C), which acts as a protease. The rate of change of [C][C] is governed by the differential equation: d[C]dt=−kdeg⋅[APC/C]⋅[C]+Synthesis Rate\frac{d[C]}{dt} = -k_{deg} \cdot [APC/C] \cdot [C] + \text{Synthesis Rate} where kdegk_{deg} is the degradation rate constant, and [APC/C][APC/C] is the concentration of the active complex. The degradation rate is assumed to follow pseudo-first-order kinetics with respect to [C][C] when [APC/C][APC/C] is saturating, simplifying the rate law to: d[C]dt=−keff[C]\frac{d[C]}{dt} = -k_{eff} [C] where keff=kdeg[APC/C]satk_{eff} = k_{deg} [APC/C]_{sat}. This decay dictates the timing of cell cycle exit.
Source: Wikipedia