Figure 3.

Stationary state distribution of monomer (black) and dimer (orange) protein abundance in the positive autogenous circuits. The left (right) column corresponds to a ratio of the dimer and monomer decay rates of γ₂/γ₁ = 1/10 (γ₂/γ₁ = 1/2). The molecular copy numbers are collected at a fixed time interval (5·10³ sec) after the steady state has been reached. Here K₁ ≡ q₁/k₁ is the dissociation constant of the protein dimer. As the binding equilibrium is shifted towards the dimer state (decreasing K₁), the noise level is monotonically reduced (see Table 2). Note that the prolonged protein lifetime due to the complex formation (left column) affects the noise level.