Intercellular Variability in Protein Levels from Stochastic Expression and Noisy Cell Cycle Processes
Fig 1
Sample trajectory of the protein level in a single cell with different sources of noise.
Stochastically expressed proteins accumulate within the cell at a certain rate. At a random point in the cell cycle, gene duplication results in an increase in production rate. Stochastic cell-division events lead to random partitioning of protein molecules between two daughter cells with each cell receiving, on average, half the number of proteins in the mother cell just before division. The steady-state protein copy number distribution obtained from a large number of trajectories is shown on the right. The total noise in the protein level, as measured by the squared coefficient of variation (CV2) can be broken into contributions from individual noise mechanisms.