ATP-sensitive potassium channel

ATP-sensitive potassium channel (or K_ATP channel) is a class of potassium channels that couples cell metabolic activity to the electrical behavior of the cell. These channels are found in many tissues including the pancreatic beta cells, neurons, cardiac cells, and smooth muscle cells.

Structure

The ATP-sensitive potassium channel is an octameric complex composed of four pore-forming Kir6.x subunits and four regulatory sulfonylurea receptor (SUR) subunits. The Kir6.x subunits form the central pore that allows potassium ions to flow through, while the SUR subunits regulate the activity of the channel.

Function

The primary function of the ATP-sensitive potassium channel is to link the metabolic state of the cell to its electrical activity. When the intracellular concentration of ATP is high, the ATP binds to the Kir6.x subunits, causing the channel to close and preventing potassium ions from leaving the cell. This results in the depolarization of the cell membrane, which can trigger a variety of cellular responses such as insulin secretion in pancreatic beta cells or vasodilation in smooth muscle cells.

Clinical significance

Mutations in the genes encoding the subunits of the ATP-sensitive potassium channel can lead to a variety of diseases. For example, mutations in the Kir6.2 subunit can cause neonatal diabetes, while mutations in the SUR1 subunit can cause hyperinsulinemic hypoglycemia. In addition, drugs that target the ATP-sensitive potassium channel, such as sulfonylureas and diazoxide, are used in the treatment of diabetes and hypertension, respectively.

See also

• Potassium channel
• Sulfonylurea receptor
• Kir6.x subunits
• ATP

References

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