BK channel

BK channel is a type of potassium channel that is activated by both voltage and intracellular calcium ions. These channels are known for their large conductance, hence the name "Big Potassium" or "BK" channel. They are found in many tissues in the body and play a crucial role in various physiological processes.

Structure

BK channels are tetramers, meaning they are composed of four subunits. Each subunit consists of seven transmembrane domains with a large extracellular loop between the fifth and sixth domains. The N-terminus and C-terminus are located intracellularly. The C-terminus contains the calcium-binding sites and the voltage sensor.

Function

BK channels are involved in a variety of physiological processes. They help regulate action potentials in neurons, control the release of neurotransmitters, and contribute to the regulation of smooth muscle tone. In the kidney, they play a role in potassium secretion and fluid balance. In the ear, they are involved in the tuning of hair cells to specific frequencies of sound.

Clinical significance

Mutations in the gene encoding the BK channel can lead to a variety of disorders. For example, gain-of-function mutations can cause epilepsy and ataxia, while loss-of-function mutations can lead to hypertension. In addition, BK channels have been implicated in the development of certain types of cancer, as they can promote cell proliferation and migration.

Pharmacology

Several drugs have been developed to modulate the activity of BK channels. These include calcium channel blockers, which inhibit the activity of the channel, and potassium channel openers, which enhance its activity. These drugs are used in the treatment of various conditions, such as hypertension, asthma, and certain neurological disorders.

See also

• Voltage-gated potassium channel
• Calcium-activated potassium channel
• Ion channel