Calcium-activated Large Conductance Potassium Channel (BK channel)

BK channels are large conductance, voltage and calcium (Ca2+)-activated potassium channels that play a critical role in repolarizing the membrane potential by allowing potassium ions to flow outward in response to membrane depolarization or increased intracellular calcium levels. This function is essential for regulating neuronal excitability, neurotransmitter release, smooth muscle contraction, vascular tone, and other physiological processes. The core BK channel is a homotetramer composed of four identical pore-forming α subunits encoded by the *KCNMA1* gene. Auxiliary β and γ subunits modulate gating properties and show tissue-specific expression. Activation requires both membrane depolarization and binding of intracellular Ca²⁺ or Mg²⁺ ions at high-affinity sites on RCK domains.

Other names

Big Potassium channelMaxi-KSlo1KCa1.1KCNMA1

Modulation of ion flow through the channel, affecting membrane potential and cellular excitability.