Potassium leak channels and the KCNK family of two-P-domain subunits

With a bang, a new family of potassium channels has exploded into view. Alt hough KCNK channels were discovered only five years ago, they already outnu mber other channel types. KCNK channels are easy to identify because of the ir unique structure - they possess two pore-forming domains in each subunit . The new channels function in a most remarkable fashion: they are highly r egulated, potassium-selective leak channels. Although leak currents are fun damental to the function of nerves and muscles, the molecular basis for thi s type of conductance had been a mystery. Here we review the discovery of K CNK channels, what has been learned about them and what lies ahead. Even th ough two-P-domain channels are widespread and essential, they were hidden f rom sight in plain view - our most basic questions remain to be answered.