Key result
Cryo-EM structures reveal that Ba2+ occupies site S3 in the selectivity filter leading to blockade, and binds at high-affinity Ca2+ sites representing intermediate transitions between closed and open states.
Cryo-EM structures elucidate the dual mechanism of Ba2+ on BK channels, showing it blocks the pore at site S3 while partially activating the channel via Ca2+ binding sites.
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No immediate clinical implications from animal structural data; extends mechanistic models of BK channel modulation for future study.
Ba 2+ increases open probability and blocks the permeation pathway of BK channels. Here we discuss Cryo-EM structures of BK channels with Ba 2+ . They reveal that Ba 2+ occupies site S3 in the selectivity filter, leading to blockade. Ba 2+ are also detected at all high affinity Ca 2+ binding sites of the gating ring. However, the architectures of this region in these structures represent intermediate transitions between the extreme close and open configurations.
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Srivastava et al. (2022) studied this question. Barium ions (Ba2+) vs. Absence of Ba2+ was evaluated on Cryo-EM structure and electrophysiological response of BK channels. Cryo-EM structures reveal that Ba2+ occupies site S3 in the selectivity filter leading to blockade, and binds at high-affinity Ca2+ sites representing intermediate transitions between closed and open states.
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