BK channel
From Freepedia
BK channels, also called MaxiK or slo channels, are large conductance Ca2+ and voltage-activated K+ channels. They belong to a group of ion channels that when activated by membrane voltage and intracellular Ca2+, allow K+ to leave the cytoplasm. This results in hyperpolarization or a decrease in cell excitability. BK channels are essential for key physiological processes. They are particularly important for controlling the contraction of smooth muscle and in invertebrates these channels are also important for electrical tuning of hair cells in the cochlea. BK channels are important for the behavioral effects of ethanol in the worm C. elegans [[1]].
BK channels are a prime example modular evolutionary protein design. The pore forming alpha subunit consists of the potassium permeable pore domain and the voltage sensing domain that are found in all other voltage gated K+ channels. In addition, BK channels carry a unique transmembrane domain that appears to mediate the interaction with a family of modulatory tissue specific (beta) subunits, and also a unique large intracellular domain that is thought to act as a sensor for the intracellular Ca2+ concentration (see the image below).
External links
- Potassium Channels
- Structure of the RCK Domain from the E. coli K+ Channel and Demonstration of Its Presence in the Human BK Channel(requires subscription
- An overview of the potassium channel family
