Intercellular Variability in Protein Levels from Stochastic Expression and Noisy Cell Cycle Processes
Fig 4
Scaling of noise as a function of the mean protein level for different mechanisms.
The contribution of random cell-division events to the noise in protein copy numbers (extrinsic noise) is invariant of the mean. In contrast, contributions from partitioning errors at the time of cell division (partitioning noise) and stochastic expression (production noise) scale inversely with the mean. The scaling factors are shown as a function of the protein random burst size B, noise in cell-cycle time () and magnitude of partitioning errors quantified by α (see Eq (5)). With increasing mean level the total noise first decreases and then reaches a baseline that corresponds to extrinsic noise. For this plot, B is assumed to be geometrically-distributed with mean 〈B〉 = 1.5,
and α = 1 (i.e., binomial partitioning).