Trypsin-sensitive, rapid inactivation of a calcium-activated potassium channel

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Science  18 Sep 1992:
Vol. 257, Issue 5077, pp. 1694-1698
DOI: 10.1126/science.1529355


Most calcium-activated potassium channels couple changes in intracellular calcium to membrane excitability by conducting a current with a probability that depends directly on submembrane calcium concentration. In rat adrenal chromaffin cells, however, a large conductance, voltage- and calcium-activated potassium channel (BK) undergoes rapid inactivation, suggesting that this channel has a physiological role different than that of other BK channels. The inactivation of the BK channel, like that of the voltage-gated Shaker B potassium channel, is removed by trypsin digestion and channels are blocked by the Shaker B amino-terminal inactivating domain. Thus, this BK channel shares functional and possibly structural homologies with other inactivating voltage-gated potassium channels.

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