ATP-sensitive potassium channel subunit (Kir6.x-SUR complex) (KATP channel)

ATP-sensitive potassium channels (KATP channels) are hetero-octameric complexes composed of four pore-forming inwardly rectifying potassium channel subunits (Kir6.x, typically Kir6.1 or Kir6.2) and four regulatory sulfonylurea receptor subunits (SUR, typically SUR1, SUR2A, or SUR2B)[5]. The Kir6.x subunit forms the ion-conducting pore, while the SUR subunit (a member of the ATP-binding cassette transporter superfamily) senses intracellular nucleotides (ATP, ADP) and mediates allosteric regulation and pharmacological modulation[1][5]. KATP channels are widely expressed in tissues including pancreatic beta cells, muscle, heart, vascular smooth muscle, and brain, where they act as metabolic sensors, coupling cellular energy status to membrane excitability and secretory activity[1][3][5]. In pancreatic beta cells, closure of KATP channels in response to elevated glucose leads to membrane depolarization, calcium influx, and insulin secretion; these channels are a major target for antidiabetic drugs such as sulfonylureas[3][5]. Different tissue-specific subunit combinations (e.g., Kir6.2/SUR1 in beta cells, Kir6.2/SUR2A in cardiac muscle, Kir6.1/SUR2B in vascular smooth muscle) confer distinct regulatory and pharmacological properties[5]. KATP channels are also implicated in cardiac ischemia, epilepsy, and genetic disorders such as congenital hyperinsulinism and neonatal diabetes[5].

Other names

ATP-sensitive potassium channelKATP channelKir6.x/SUR complexInwardly rectifying potassium channel KIR6.xSulfonylurea receptorSUR/Kir6.x channelMetabolic sensing potassium channel

ATP binding to the Kir6.x subunit inhibits channel opening, closing the pore; ADP binding to the SUR subunit promotes channel opening; Sulfonylureas bind SUR1 to inhibit channel activity, promoting insulin secretion in pancreatic beta cells; Potassium channel openers bind SUR2 to promote channel opening, hyperpolarizing the membrane; Antidiabetic drugs act by blocking KATP channels in beta cells, depolarizing the membrane and triggering insulin release