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

ATP-sensitive potassium (KATP) channels containing the Sulfonylurea receptor 2 (SUR2) subunit are hetero-octameric protein complexes that function as metabolic sensors, coupling cellular energy levels to membrane potential [1]. These channels consist of four pore-forming subunits (typically Kir6.1 or Kir6.2) and four regulatory SUR2 subunits encoded by the ABCC9 gene [2]. SUR2 is expressed in two major isoforms: SUR2A, found primarily in cardiac and skeletal muscle, and SUR2B, found in vascular and non-vascular smooth muscle [4]. When intracellular ATP levels drop or ADP levels rise, these channels open, causing potassium efflux and membrane hyperpolarization, which leads to smooth muscle relaxation and vasodilation [3]. Clinically, SUR2-containing channels are targeted by potassium channel openers like minoxidil for hypertension and nicorandil for angina [3]. Mutations in the ABCC9 gene are linked to Cantu syndrome, characterized by hypertrichosis and cardiovascular abnormalities, as well as certain forms of cardiomyopathy [2]. The channel's ability to protect the myocardium during ischemia makes it a significant target for cardioprotective drug development [4]. Conversely, inhibition of these channels by sulfonylureas like glibenclamide can affect vascular tone and cardiac response to stress [1].

Other names

SUR2-containing KATP channelABCC9-containing potassium channelKATP channel (SUR2A/B)Sulfonylurea receptor 2-containing potassium channel

Potassium channel openers (KCOs) bind to the SUR2 regulatory subunit, which facilitates the opening of the Kir6.x pore [3]. This results in an increase in potassium conductance, leading to hyperpolarization of the plasma membrane [4]. In vascular smooth muscle, this hyperpolarization closes voltage-gated calcium channels, reducing calcium influx and causing vasodilation [3].