Voltage-gated potassium channel

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

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. The four subunits can be identical (homotetrameric) or different (heterotetrameric), leading to a diversity of channel types with different properties.

Function

The primary function of VGKCs is to regulate the flow of potassium ions across the cell membrane. When the membrane potential becomes more positive, the S4 segment moves outward, triggering a conformational change that opens the channel. This allows potassium ions to flow out of the cell, repolarizing the membrane and ending the action potential. VGKCs are also involved in shaping the action potential and setting the resting membrane potential.

Clinical significance

Mutations in the genes encoding VGKCs can lead to a variety of channelopathies, including episodic ataxia, benign familial neonatal seizures, and certain forms of epilepsy. In addition, antibodies against VGKCs have been implicated in autoimmune diseases such as Lambert-Eaton syndrome and Neuromyotonia.

See also

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

References

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