Polyamine block of kir channels: Toward a molecular picture

Potassium channels are transmembrane proteins that selectively allow K ⁺ ions to pass from one side of the membrane to the other. Most K⁺ channels exhibit a property termed rectification, which as a general physical term refers to a voltage dependence of conductance or resistance. In the context of biophysical studies of ion channels, this term is used to describe a voltage dependence of macroscopic currents in which currents through an ion channel flow preferentially into the cell (inward rectification) or out of the cell (outward rectification).