SK channel

SK channel is a type of potassium channel that is activated by an increase in intracellular calcium ion concentration. These channels are found in many tissues, including the brain, heart, and smooth muscle.

Structure

SK channels are composed of four subunits, each of which has six transmembrane domains. The pore of the channel, through which potassium ions pass, is formed by the loop between the fifth and sixth transmembrane domains of each subunit. The calcium-sensing domain is located on the cytoplasmic side of the channel.

Function

SK channels play a crucial role in regulating the electrical activity of cells. When the concentration of calcium ions inside the cell increases, these channels open, allowing potassium ions to flow out of the cell. This outward flow of positive charges hyperpolarizes the cell, making it less likely to fire an action potential. In this way, SK channels help to control the excitability of cells.

In the brain, SK channels are involved in the regulation of neuronal excitability and the release of neurotransmitters. In the heart, they contribute to the repolarization of the cardiac action potential. In smooth muscle, they help to regulate muscle tone.

Clinical significance

Mutations in the genes encoding SK channels can lead to a variety of diseases. For example, mutations in the KCNN3 gene, which encodes the SK3 channel, have been associated with schizophrenia and bipolar disorder. In addition, drugs that modulate the activity of SK channels are being developed for the treatment of neurological and cardiovascular diseases.

See also

• Voltage-gated potassium channel
• Calcium-activated potassium channel
• Inward-rectifier potassium channel

References

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