Figure 7

Estimation of response time constants from autocorrelation functions. The concentrations of free and bound TFs (X and P _b respectively) fluctuate stochastically for the MIP shown in Fig. 3A. The total TF concentration (X + P _b ) can be observed experimentally; for example, when the TF is tagged for fluorescence, the fluorescence intensity could reflect the total TF concentration [43]. The autocorrelation of the total is fitted to an exponential function: A linear fit is taken in the semi-log scale. The inverse of the fitted slope corresponds to the response time constant ${\tau }_{P_T}$. The error bar of the ${\tau }_{P_T}$ are estimated from 10 independent replicates of autocorrelation functions (only three samples are shown in the figure). The same parameter values are used as in the Fig. 4 caption and the value of P _T is set to 100.