SMALL-CONDUCTANCE, CALCIUM-ACTIVATED POTASSIUM CHANNELS FROM MAMMALIAN BRAIN

Members of a previously unidentified family of potassium channel subun its were cloned from rat and human brain. The messenger RNAs encoding these subunits were widely expressed in brain with distinct yet overla pping patterns, as well as in several peripheral tissues. Expression o f the messenger RNAs in Xenopus oocytes resulted in calcium-activated, voltage-independent potassium channels. The channels that formed from the various subunits displayed differential sensitivity to apamin and tubocurare. The distribution, function, and pharmacology of these cha nnels are consistent with the SK class of small-conductance, calcium-a ctivated potassium channels, which contribute to the afterhyperpolariz ation in central neurons and other cell types.