ATP-binding cassette domain of the sulfonylurea receptor, subfamily C
The SUR domain 1. The sulfonylurea receptor SUR is an ATP transporter of the ABCC/MRP family with tandem ATPase binding domains. Unlike other ABC proteins, it has no intrinsic transport function, neither active nor passive, but associates with the potassium channel proteins Kir6.1 or Kir6.2 to form the ATP-sensitive potassium (K(ATP)) channel. Within the channel complex, SUR serves as a regulatory subunit that fine-tunes the gating of Kir6.x in response to alterations in cellular metabolism. It constitutes a major pharmaceutical target as it binds numerous drugs, K(ATP) channel openers and blockers, capable of up- or down-regulating channel activity.