The Energetic Cost of Different Biological Strategies to Transfer Information*

One of the primary computational requirements of a cellular system is the ability to transfer information between spatially separated components. In real systems, there is a wide variety of qualitatively different physical strategies for accomplishing this task, each suited to a different set of constraints. Electrical signaling is used by ion channels to communicate with voltage sensitive receptors. Diffusive signaling is used by kinases which produce second messengers which travel either through the membrane or bulk to reach a target. Order parameters of phase transitions are used to localize targets to specific regions. For each strategy, an energy consuming sender transmits a signal by modifying its local environment and the signal is broadcast to distant receivers. Here we explore the energetic cost of sending a signal as a function of frequency and spatial separation between the sender and receiver in the context of these strategies, computing a lower bound on the energetic cost of sending a bit of information. This tradeoff between energy and information, driven by the different physical constraints, may explain why cells use diverse strategies for different signaling purposes.