Two-pore-domain potassium channel

File:Two-pore domain potassium channel K2P1 PDB-3ukm.png

Structure of K2P1 channel

File:Two-pore domain potassium channel K2P2 PDB-4twk.png

Structure of K2P2 channel

File:Two-pore domain potassium channel K2P3 PDB-6rv3.png

Structure of K2P3 channel

Two-pore-domain potassium channels, also known as K2P channels, are a class of potassium channels that are characterized by having two pore-forming domains in each subunit. These channels are responsible for setting and regulating the resting membrane potential of cells and are involved in various physiological processes.

Structure

K2P channels are unique among potassium channels due to their structure, which includes two pore-forming domains per subunit. This structural feature allows them to form dimers, creating a functional channel with four pore domains. The channels are generally composed of four transmembrane segments and two pore loops, which contribute to the selectivity filter that allows potassium ions to pass through while excluding other ions.

Function

The primary function of two-pore-domain potassium channels is to maintain the resting membrane potential and contribute to the background potassium conductance in cells. They are often referred to as "leak" channels because they allow a constant, passive flow of potassium ions across the cell membrane. This flow is crucial for stabilizing the membrane potential and modulating cellular excitability.

K2P channels are involved in various physiological processes, including neuronal excitability, cardiac function, and pain perception. They are also sensitive to a range of physical and chemical stimuli, such as changes in pH, temperature, and mechanical stretch, which can modulate their activity.

Types

There are several subfamilies of K2P channels, each with distinct properties and regulatory mechanisms. Some of the well-known subfamilies include:

• K2P1 (TWIK-1): The first identified member of the K2P family, involved in setting the resting membrane potential.
• K2P2 (TREK-1): Known for its sensitivity to mechanical stretch and temperature changes.
• K2P3 (TASK-1): Plays a role in pH sensing and is involved in respiratory control.

Clinical significance

Mutations and dysregulation of K2P channels have been implicated in various diseases, including neurological disorders, cardiac arrhythmias, and cancer. As such, they are considered potential targets for therapeutic intervention.

Related pages

• Potassium channel
• Ion channel
• Membrane potential