Signaling Tug-of-War Delivers the Whole Message

Abstract

SUMMARYHow do cells transmit biochemical signals accurately? It turns out, pushing and pulling can go a long way. MAIN TEXTCells trigger many of their functions in response to environmental signals. In this issue, Andrews et al. (2016) study how signalling reactions should be coupled to one another to accurately transmit signals from outside to inside the cell. They propose that a simple push-pull mechanism is sufficient for cells to produce precise readouts of external signals. In this mechanism, the active form of a signalling molecule 'pushes' up the concentration of a molecule downstream, while the inactive form inactive 'pulls' it back.These opposing effects align the activity levels of signalling molecules along a pathway and result in a proportional relation between receptor activation and downstream signal strength. The study casts new light on design principles of cellular signalling, and opens up plenty of questions for further research.Cells have membrane receptors that relay external signals into the intracellular space.External ligands bind to these receptors and trigger signalling reactions such as mitogen-