Kir6.2 is a member of the inward rectifier K+ channels (Kir channels), a large family of voltage-independent K+ channels largely involved in stabilization of the membrane resting potential and in K+ transport across membranes. Kir channels can be modulated by a variety of intracellular agents such as protons, GTP-binding proteins and adenine nucleotides.
The ATP-sensitive channel (KATP) is especially important since it couples cellular metabolism (intracellular ATP levels) with cell excitability. KATP channels have been described in pancreatic b-cells, neurons, heart, skeletal and smooth muscle.
The KATP channel is composed of a Kir6.2 or Kir6.1 subunit and a sulphonylurea receptor (SUR) subunit.
The pancreatic KATP channel for example, is composed of a complex of Kir6.2 and SUR1 subunits, while the cardiac KATP channel is composed of Kir6.2 and SUR2A complexes.
Impaired b-cell KATP channel function due to mutations in either Kir6.2 or SUR1 subunits has been linked to the recessive autosomal disorder called persistent hyperinsulinemic hypoglycemia of infancy (PHHI). In addition, a Kir6.2 variant has recently been linked to an increased risk of developing type-2 diabetes.
