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voltage-gated ion channel

Wednesday 26 January 2005

Voltage-gated ion channels are activated and inactivated by changes in transmembrane potential.

Voltage-gated ion channels are identified according to the principal ion conducted through the channel (e.g., sodium, potassium, calcium, or chloride), and are concentrated in different regions of neurons according to their principal function.

Voltage-gated sodium channels are in high concentration in the axon hillock, to generate the action potential. The nodes of Ranvier contain a high concentration of both sodium and potassium channels to regenerate the action potential. The axon terminals contain a large concentration of calcium channels, to permit the ready release of neurotransmitters.

The different voltage-gated channels contain six transmembrane regions, S1-S6. The subunits are assembled to form a central pore. The specific structure of this central pore determines the selective permeability of the channel to a particular ion. The regions between S5 and S6 of the different subunits line the channel pore and determine this selectivity. The S4 transmembrane domain of the different subunits forms the voltage sensor.

Voltage-gated channels have several roles. The potassium channels are primarily responsible for the establishment of resting membrane potential and the repolarization of cells after an action potential. The sodium channels serve primarily in the generation of the action potential (i.e., fast depolarization).

The calcium channels are implicated in the generation of the action potential in the heart and smooth muscles, muscle contraction, neurotransmitter release, and intracellular signaling (i.e., second messenger). Certain chloride channels are voltage-gated and are involved in the hyperpolarization of cells.

Exemples

- voltage-gated sodium channels
- voltage-gated potassium channels
- voltage-gated calcium channels
- voltage-gated chloride channels

References

- Schwappach B. An overview of trafficking and assembly of neurotransmitter receptors and ion channels (Review). Mol Membr Biol. 2008 May;25(4):270-8. PMID: 18446613

- Arikkath J, Campbell KP. Auxiliary subunits: essential components of the voltage-gated calcium channel complex. Curr Opin Neurobiol. 2003 Jun;13(3):298-307. PMID: 12850214

- Sands Z, Grottesi A, Sansom MS. Voltage-gated ion channels. Curr Biol. 2005 Jan 26;15(2):R44-7. PMID: 15668152