ATP-sensitive potassium channel (SUR2B-containing) (KATP (SUR2B))

The ATP-sensitive potassium (KATP) channel containing the SUR2B subunit is a hetero-octameric protein complex that serves as a vital regulator of vascular and non-vascular smooth muscle tone. It is composed of four pore-forming subunits, typically Kir6.1 (KCNJ8), and four regulatory sulfonylurea receptor 2B (SUR2B) subunits, which are encoded by the ABCC9 gene (UniProt: O60706). These channels function as metabolic sensors, opening in response to a decrease in the intracellular ATP/ADP ratio to cause potassium efflux and membrane hyperpolarization. This hyperpolarization leads to the closure of voltage-gated calcium channels, resulting in smooth muscle relaxation and vasodilation (PubMed: 10484331). SUR2B-containing complexes are the primary targets for potassium channel openers (KCOs) such as minoxidil and pinacidil, which are used clinically to manage refractory hypertension. Beyond the vasculature, these channels are also found in the bladder and bronchi, influencing organ-specific contractility. Mutations in the ABCC9 gene that affect SUR2B function are associated with Cantu syndrome, characterized by hypertrichosis and cardiovascular abnormalities (PubMed: 22723354). Consequently, these complexes are significant therapeutic targets for cardiovascular and potentially urological disorders.

Other names

Sulfonylurea receptor 2B-containing KATP channelVascular ATP-sensitive potassium channelABCC9-SUR2B complexKir6.1/SUR2B channelKir6.2/SUR2B channel

Potassium channel openers bind to the SUR2B regulatory subunit, increasing the open-state probability of the channel, which leads to potassium efflux, membrane hyperpolarization, and subsequent relaxation of smooth muscle cells.