Principles of selective ion transport in channels and pumps. Science 310, 1461–1465. doi: 10.1126/science.1113666

The transport of ions across the membranes of cells and organelles is a prerequisite for many of life’s processes. Transport often involves very precise selectivity for spe-cific ions. Recently, atomic-resolution structures have been determined for channels or pumps that are selective for sodium, potassium, calcium, and chloride: four of the most abundant ions in biology. From these structures we can begin to understand the principles of selective ion transport in terms of the architecture and detailed chem-istry of the ion conduction pathways. The flow of ions across the cell membrane is essential to many of life_s processes. Ion pumps build gradients across the membrane, which are then used as an energy source by ion channels and other transport proteins to pump nutrients into cells, generate electrical signals, regulate cell volume, and secrete elec-trolytes across epithelial layers (1). Life de