ATP-sensitive K Channels
An ATP-sensitive potassium channel (or KATP channel) is a type of potassium channel that is gated by intracellular nucleotides, ATP and ADP. ATP-sensitive potassium channels are composed of Kir6.x-type subunits and sulfonylurea receptor (SUR) subunits, along with additional components. KATP channels are found in the plasma membrane; however some may also be found on subcellular membranes. These latter classes of KATP channels can be classified as being either sarcolemmal ("sarcKATP"), mitochondrial ("mitoKATP"), or nuclear ("nucKATP"). Discovery and structure KATP channels were first identified in cardiac myocytes by the Akinori Noma group in Japan. 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 fo ...
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