Membrane-Associated Self-Assembly for Cellular Decision Making.

Cellular decision-making based on information received from the external environment is frequently initiated by transmembrane receptors. These receptors are known to propagate such information by triggering a series of irreversible, energy-consuming reactions. While this active mechanism ensures switch-like responses, here we show how spontaneous molecular self-assembly on a two-dimensional substrate can similarly act as a tunable and robust switch for detecting receptors at physiological concentrations. This mechanism is much more sensitive than other passive mechanisms for receptor detection. We derive analytical expressions for critical receptor densities that switch on nucleation and growth of assemblies, in close agreement with equilibrium stochastic reaction-diffusion simulations. The theory developed provides testable predictions for how each component controls decision thresholds and magnitude of response.