FIG. 5. Clustering reduces time to precise concentration interpretation.

(A, B) Two cartoons show Bcd molecules in the nucleus (green circles) and an enhancer with a binding site of length $b$ (A) or a cluster of diameter $d$ (B) embedded in the nuclear environment. The equation in (A) is for the time taken by a sensor of size $a$ for nuclear concentration $c$ with an accuracy of $\left(\frac{dN}{N}\right)$, where $N$ is the number of molecules counted. (C) Reduction of time ($g_T$) to make an accurate (~ 10%) nuclear concentration estimation as a function of the nuclear position with the cluster as nuclear concentration sensor versus an enhancer binding site being the concentration sensor [35].