Ion Channels

Ion channels catalyze the transmembrane movement of small inorganic ions across biological membranes. They do so by forming continuous, hydrophilic pores through which ions can cross the barrier imposed by the lipid bilayer hydrophobic core. Ion channels serve many functions: they underlie the changes in membrane potential that control many cell functions, including the propagated electrical signaling (the action potentials) in electrically excitable cells; they allow for the bulk movement of ions across cell membranes. In this article we summarize key features of ion channels, with special emphasis on the channels in the plasma membrane—their structure and catalytic power, the generation of membrane potential changes, the regulation (or gating) that underlies normal channel function, and how channel function can be modulated by small molecules.