Toward linking structure with function in ATP-sensitive K+ channels

Diabetes. 2004 Dec:53 Suppl 3:S104-12. doi: 10.2337/diabetes.53.suppl_3.s104.

Abstract

Advances in understanding the overall structural features of inward rectifiers and ATP-binding cassette (ABC) transporters are providing novel insight into the architecture of ATP-sensitive K+ channels (KATP channels) (KIR6.0/SUR)4. The structure of the K(IR) pore has been modeled on bacterial K+ channels, while the lipid-A exporter, MsbA, provides a template for the MDR-like core of sulfonylurea receptor (SUR)-1. TMD0, an NH2-terminal bundle of five alpha-helices found in SURs, binds to and activates KIR6.0. The adjacent cytoplasmic L0 linker serves a dual function, acting as a tether to link the MDR-like core to the KIR6.2/TMD0 complex and exerting bidirectional control over channel gating via interactions with the NH2-terminus of the KIR. Homology modeling of the SUR1 core offers the possibility of defining the glibenclamide/sulfonylurea binding pocket. Consistent with 30-year-old studies on the pharmacology of hypoglycemic agents, the pocket is bipartite. Elements of the COOH-terminal half of the core recognize a hydrophobic group in glibenclamide, adjacent to the sulfonylurea moiety, to provide selectivity for SUR1, while the benzamido group appears to be in proximity to L0 and the KIR NH2-terminus.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • ATP-Binding Cassette Transporters / metabolism
  • Adenosine Triphosphate / physiology*
  • Animals
  • Humans
  • Hypoglycemic Agents / pharmacology
  • Models, Molecular
  • Potassium Channels / chemistry*
  • Potassium Channels / drug effects
  • Potassium Channels / physiology*
  • Potassium Channels, Inwardly Rectifying / chemistry
  • Potassium Channels, Inwardly Rectifying / drug effects
  • Potassium Channels, Inwardly Rectifying / physiology
  • Protein Conformation

Substances

  • ATP-Binding Cassette Transporters
  • Hypoglycemic Agents
  • Kir6.2 channel
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Adenosine Triphosphate