The membranes of all living cells contain proteins called ion channels that allow ions to move in and out of the cells. The flow of ions through those channels helps to regulate the electrostatic potential difference across a cell’s membrane.
In the case of multicellular organisms, cells communicate with each other by opening and closing specialized channels that let only specific ions through. For example, the coordinated opening and closing of sodium and potassium channels and the associated inflow of Na+ and outflow of K+ propagate a positive voltage pulse—a nerve impulse—down a neuron.
Single-cell organisms such as bacteria also contain various ion-specific channels. In fact, biologists have gained much of what they know about the structure and function of ion channels by looking at proteins harvested from bacteria. What the bacteria use them for has long been a puzzle.
Gürol Süel (University of California, San Diego) and...
