 They have also been found in pancreas where they control insulin secretion, but are in fact widely distributed in plasma membranes.SarcKATP are composed of eight protein subunits (octamer).Four of these are members of the inward-rectifier potassium ion channel family Kir6.x (either Kir6.1 or Kir6.2), while the other four are sulfonylurea receptors (SUR1, SUR2A, and SUR2B).