ATP-sensitive potassium channel (Sulfonylurea receptor 2-containing) (KATP (SUR2))

ATP-sensitive potassium (KATP) channels are hetero-octameric complexes consisting of four pore-forming inwardly rectifying potassium channel subunits (Kir6.1 or Kir6.2) and four regulatory sulfonylurea receptor subunits (SUR1 or SUR2) (NIH, 2016). SUR2-containing complexes, encoded by the ABCC9 gene, are primarily expressed in the heart (SUR2A isoform), skeletal muscle, and vascular smooth muscle (SUR2B isoform) (MedlinePlus, 2013; PubMed, 2024). These channels function as metabolic sensors that couple the intracellular ATP/ADP ratio to membrane excitability, opening in response to metabolic stress to hyperpolarize the cell and reduce energy consumption (NIH, 2013). In the vasculature, SUR2B-containing channels are critical regulators of vascular tone and blood pressure, while SUR2A-containing channels in the heart mediate ischemic preconditioning and protect against myocardial injury (PubMed, 2022; NIH, 2013). Mutations in the SUR2 subunit are associated with clinical conditions such as Cantu syndrome, characterized by hypertrichosis and cardiovascular defects, and dilated cardiomyopathy (MedlinePlus, 2013; NIH, 2024). Pharmacological modulation involves potassium channel openers like pinacidil for treating hypertension and angina, as well as sulfonylurea inhibitors, although achieving tissue-specific selectivity remains a significant therapeutic challenge (PubMed, 2024; NIH, 2022).

Other names

SUR2-containing KATP channelABCC9-containing KATP channelVascular KATP channelCardiac KATP channelSulfonylurea receptor 2 complex

Potassium channel openers bind to the transmembrane domain of the SUR2 subunit, stabilizing the nucleotide-binding domain (NBD) dimerized state and increasing the open probability of the Kir6.x pore, which leads to potassium efflux and membrane hyperpolarization (NIH, 2022; PubMed, 2016). Conversely, sulfonylurea blockers bind to the SUR subunit to inhibit channel opening, causing membrane depolarization (NIH, 2024; PubMed, 2013).