Figure 1.
Schematic view of the self-repressing gene network. (A) Biochemical reactions composing the network. P, M, G, and G:P denote protein, mRNA, free gene, and bound gene chemical species, respectively. The kinetic constants of the reactions are indicated, with Ω denoting cell volume. In the limit where Ω is large, the mRNA and protein copy numbers become macroscopic variables, with decreasing fluctuations; this is in comparison to the gene state, which remains microscopic and displays full-scale variations. (B) Block diagram representation of the network, consisting of a random telegraph signal generator representing the gene state-flip dynamics, and of a low-pass filter of cut-off frequency ωc representing proteins and mRNA dynamics. The telegraph signal regulates its frequency and duty cycle through feedback from the low-pass filter.