Noisy Signal Transduction in Cellular Systems.

Stochastic fluctuations of chemical reactions are particularly prominent in small systems such as cells. Such fluctuations of cellular signal processes have been observed directly by single-molecule imaging. Recent theoretical studies have also revealed that stochastic cellular reactions generate fluctuations in the number of a molecule, which can be related to their functioning such as amplification of signals. Here, we study how large each signal reaction generates and amplifies the stochastic fluctuations. The general framework of fluctuation response relation in non-equilibrium physics throws light upon this problem. The result has been applied to the chemotactic signal processing of eukaryotic cell, such as Dictyostelium cell, revealing that the accuracy of chemotaxis is determined by the signal to noise ratio in the signal of the reaction between G-protein and G-protein coupled receptor. [ABSTRACT FROM AUTHOR]