BK channel

From Free net encyclopedia

BK channels, also called MaxiK or slo1 channels, are large conductance Ca²⁺ and voltage-activated K⁺ channels, which allow K⁺ to leave the cytoplasm under physiological conditions when activated by membrane voltage and/or intracellular Ca²⁺ Template:Ref N. 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 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 Template:Ref N.

Structure

Image:Bkchannel.jpg

BK channels are a prime example of modular evolutionary protein design. The pore forming α-subunit consists of:

1. The K⁺ permeable pore domain.
2. The voltage sensing domain that are found in all other voltage gated K⁺ channels.
3. A RCK domain that is involved in regulating the K⁺ conductance Template:Ref N.
4. A unique transmembrane domain that appears to mediate the interaction with a family of modulatory tissue specific β-subunits.
5. A unique large intracellular domain that is thought to act as a sensor for the intracellular Ca²⁺ concentration Template:Ref N.

External links

• Potassium Channels

References

1. Template:Note N A central role of the BK potassium channel in behavioral responses to ethanol in C. elegans. Cell. 2003 Dec 12;115(6):655-66; Template:PMID
2. Template:Note N Image:Free text.png A novel calcium-sensing domain in the BK channel. Biophys J. 1997 Sep;73(3):1355-63; Template:PMID Template:PMID free
3. Template:Note N Image:Free text.png Structure of the RCK domain from the E. coli K+ channel and demonstration of its presence in the human BK channel. ; Template:PMID Free text
4. Template:Note N Image:Free review.png An overview of the potassium channel family. Genome Biol. 2000; 1(4):reviews0004.1-0004.5; Template:PMID Template:PMID free