Beta1 subunits facilitate gating of BK channels by acting through the Ca2+, but not the Mg2+, activating mechanisms.

ABSTRACT: The beta1 subunit of BK (large conductance Ca2+ and voltage-activated K+) channels is essential for many key physiological processes, such as controlling the contraction of smooth muscle and the tuning of hair cells in the cochlea. Although it is known that the beta1 subunit greatly increases the open probability of BK channels, little is known about its mechanism of action. We now explore this mechanism by using channels in which the Ca2+- and Mg2+-dependent activating mechanisms have been disrupted by mutating three sites to remove the Ca2+ and Mg2+ sensitivity. We find that the presence of the beta1 subunit partially restores Ca2+ sensitivity to the triply mutated channels, but not the Mg2+ sensitivity. We also find that the beta1 subunit has no effect on the Mg2+ sensitivity of WT BK c

SUBMITTER: Qian X 

PROVIDER: S-EPMC187764 | biostudies-literature | 2003 Aug

REPOSITORIES: biostudies-literature