Key result
BKCa channels affinity-purified from rat brain assemble into macromolecular complexes with Cav channels, reconstituting a functional Ca2+ nanodomain that enables rapid membrane hyperpolarization.
BKCa channels form macromolecular complexes with voltage-gated calcium channels, enabling rapid, localized calcium signaling that controls neuronal firing and transmitter release.
Large-conductance calcium- and voltage-activated potassium channels (BKCa) are dually activated by membrane depolarization and elevation of cytosolic calcium ions (Ca2+). Under normal cellular conditions, BKCa channel activation requires Ca2+ concentrations that typically occur in close proximity to Ca2+ sources. We show that BKCa channels affinity-purified from rat brain are assembled into macromolecular complexes with the voltage-gated calcium channels Cav1.2 (L-type), Cav2.1 (P/Q-type), and Cav2.2 (N-type). Heterologously expressed BKCa-Cav complexes reconstitute a functional "Ca2+ nanodomain" where Ca2+ influx through the Cav channel activates BKCa in the physiological voltage range with submillisecond kinetics. Complex formation with distinct Cav channels enables BKCa-mediated membrane hyperpolarization that controls neuronal firing pattern and release of hormones and transmitters in the central nervous system.
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Berkefeld et al. (2006) studied this question. BKCa channels affinity-purified from rat brain assemble into macromolecular complexes with Cav channels, reconstituting a functional Ca2+ nanodomain that enables rapid membrane hyperpolarization.
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