ATP-sensitive potassium channel (K_ATP channel) (K_ATP)

The ATP-sensitive potassium (K_ATP) channel is a hetero-octameric protein complex that functions as a metabolic sensor, coupling the intracellular ATP/ADP ratio to membrane potential (UniProt: Q09428, Q14654). In pancreatic beta cells, the channel consists of four pore-forming inwardly rectifying potassium channel subunits (Kir6.2) and four regulatory Sulfonylurea Receptor 1 (SUR1) subunits (PubMed: 15102361). When glucose levels rise, the resulting increase in ATP causes the channel to close, leading to membrane depolarization, calcium influx, and insulin secretion (StatPearls: Sulfonylureas). Gliclazide is a second-generation sulfonylurea that binds with high affinity to the SUR1 subunit, effectively closing the channel to stimulate insulin release in patients with type 2 diabetes (PubChem: CID 3475). Mutations in the genes encoding these subunits (ABCC8 and KCNJ11) are associated with disorders such as neonatal diabetes and congenital hyperinsulinism (NIH: Genetic Home Reference). Beyond the pancreas, K_ATP channels are also present in cardiac and skeletal muscle, as well as the brain, where they play roles in protecting against ischemic stress (PubMed: 10429837).

Other names

Sulfonylurea receptor 1SUR1ABCC8Kir6.2KCNJ11Inwardly rectifying potassium channel 6.2K_ATP channelKATP channel

Gliclazide binds to the SUR1 regulatory subunit of the K_ATP channel complex with high affinity. This binding induces a conformational change that closes the Kir6.2 pore, thereby inhibiting the efflux of potassium ions. The resulting accumulation of intracellular potassium leads to cell membrane depolarization, which triggers the opening of voltage-gated L-type calcium channels. The subsequent influx of calcium ions promotes the exocytosis of insulin-containing granules from the pancreatic beta cells into the bloodstream (PubMed: 10429837; StatPearls: Gliclazide).