SUR, ABC proteins targeted by KATP channel openers

The sulfonylurea receptor SUR is an ATP binding cassette (ABC) protein of the ABCC/MRP family. 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 which 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. We here review current knowledge on the molecular basis of the interaction of classical K(ATP) channel openers (cromakalim, pinacidil, diazoxide) with SUR.