Sulfonylurea receptor 1-Inwardly rectifying potassium channel 6.2 complex (SUR1-Kir6.2)

The Sulfonylurea receptor 1-Inwardly rectifying potassium channel 6.2 (SUR1-Kir6.2) complex is a hetero-octameric ATP-sensitive potassium (KATP) channel that acts as a key metabolic sensor in pancreatic beta-cells and neurons [1, 2]. It consists of four pore-forming Kir6.2 subunits and four regulatory SUR1 subunits, which together couple the intracellular ATP/ADP ratio to the cell's membrane potential [4, 9]. Under high-glucose conditions, increased ATP levels lead to channel closure, causing membrane depolarization and the subsequent release of insulin [11, 14]. Mutations in the genes encoding these subunits, ABCC8 and KCNJ11, are associated with significant clinical disorders including neonatal diabetes and congenital hyperinsulinism [4, 13]. This channel is the primary pharmacological target for sulfonylureas and meglitinides used to treat type 2 diabetes, as well as diazoxide, which is utilized to manage excessive insulin secretion [2, 10]. Drugs such as glibenclamide bind to the SUR1 subunit to inhibit the channel, whereas openers like diazoxide stabilize the open state to prevent depolarization [2, 6]. The precise regulation of this channel is essential for maintaining glucose homeostasis and preventing metabolic dysfunction [5, 8].

Other names

KATP channelPancreatic ATP-sensitive potassium channelABCC8-KCNJ11 complexBeta-cell KATP channel

The channel functions as a metabolic sensor where ATP binding to Kir6.2 inhibits the channel and Mg-nucleotide binding to SUR1 activates it [4, 5]. Sulfonylurea and meglitinide drugs bind to the SUR1 subunit to induce channel closure, leading to membrane depolarization, calcium influx, and insulin release [2, 6]. Conversely, channel openers like diazoxide bind to SUR1 to maintain the channel in an open state, hyperpolarizing the cell and inhibiting insulin secretion [2, 12].