Figure 4

Power spectral density (PSD) of fluctuations in protein abundance. The PSD of the MO circuit clearly displays a power-law behavior. All other model systems with an available cytosolic protein dimer state (DA1 shown here) develop a plateau in the mid-frequency region regardless of the model details (see Supplementary Information). As the dimer binding affinity increases, the noise level is further reduced. We have included the MO result in the dimer panel (right) for reference. Datasets with solid (empty) symbols correspond to γ₂/γ₁ = 1/10 (γ₂/γ₁ = 1/2).