ATP-binding cassette sub-family C member 9 (SUR2A) (SUR2A)

The ATP-binding cassette sub-family C member 9 (ABCC9), specifically the Sulfonylurea receptor 2A (SUR2A) isoform, is a critical regulatory subunit of the ATP-sensitive potassium (KATP) channel in cardiac and skeletal muscle [1.2.2, 1.4.4]. It assembles with the pore-forming subunit Kir6.2 to form a hetero-octameric complex that acts as a metabolic sensor, coupling the cell's energy status to its electrical activity [1.3.2, 1.4.2]. Under physiological conditions, high intracellular ATP levels keep the channel closed; however, during metabolic stress or myocardial ischemia, a decrease in the ATP/ADP ratio triggers SUR2A to open the channel [1.1.1, 1.3.3]. This opening results in potassium efflux and membrane hyperpolarization, which shortens the cardiac action potential duration and reduces calcium influx, thereby protecting the heart from injury [1.1.3, 1.3.4]. Mutations in the ABCC9 gene are associated with various conditions, including Cantu syndrome, dilated cardiomyopathy, and familial atrial fibrillation [1.3.2, 1.4.4]. Pharmacological modulation of SUR2A, using potassium channel openers like nicorandil for cardioprotection or blockers like glibenclamide for antiarrhythmic effects, is a significant area of cardiovascular research [1.1.2, 1.3.1].

Other names

Sulfonylurea receptor 2SUR2ABCC9Sulfonylurea receptor 2AATP-binding cassette sub-family C member 9

SUR2A serves as the regulatory subunit of the cardiac KATP channel, where it senses the intracellular ATP/ADP ratio to regulate the opening of the Kir6.2 pore [1.2.2, 1.3.2]. Under normal conditions, high ATP levels keep the channel closed, but during metabolic stress or ischemia, the binding of Mg-ADP to the nucleotide-binding domains (NBDs) of SUR2A promotes channel opening [1.3.2, 1.3.3]. This leads to potassium efflux, membrane hyperpolarization, and a shortening of the action potential duration, which reduces calcium influx and protects the myocardium from injury [1.1.3, 1.3.4]. Drugs targeting SUR2A act either as potassium channel openers (KCOs), which stabilize the open state to provide cardioprotection, or as blockers, which inhibit the channel to prevent ischemia-induced arrhythmias [1.1.2, 1.3.5].