Voltage-gated potassium channels

Voltage-gated potassium channels (VGKCs) are a type of potassium channel that open or close in response to changes in the electrical membrane potential across the cell membrane. They play a crucial role in the action potential of excitable cells such as neurons, muscle cells, and endocrine cells.

Structure

Voltage-gated potassium channels are composed of four subunits, each of which has six transmembrane segments (S1-S6). The S4 segment acts as the voltage sensor, while the S5-S6 segments form the pore through which potassium ions pass.

Function

The primary function of VGKCs is to regulate the flow of potassium ions (K+) across the cell membrane. When the membrane potential becomes more positive, the channels open, allowing K+ to flow out of the cell. This outward flow of positive ions makes the inside of the cell more negative, repolarizing the membrane and ending the action potential. This process is crucial for the proper functioning of the nervous system and the heart.

Clinical significance

Mutations in the genes encoding VGKCs can lead to a variety of diseases, including epilepsy, ataxia, and Long QT syndrome. In addition, antibodies against VGKCs have been implicated in autoimmune diseases such as Lambert-Eaton syndrome and Isaacs' syndrome.

See also

• Ion channel
• Voltage-gated ion channel
• Potassium channelopathy

References

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