A general framework for achieving integral control in chemotactic biological signaling mechanisms

The ability to sense gradients is important for proper functioning of single cell organisms and multi-cellular systems. Most known chemotactic systems are capable of perfect adaptation to spatially uniform changes in the chemoattractant concentration. In control-theoretic terms, this amounts to a step disturbance rejection problem. Thus, cells must be able to implement integral control mechanisms for rejecting these steps. We describe two general frameworks for achieving integral control in signal transduction pathways.