Polyamines as gating molecules of inward-rectifier K+ channels.
Inward-rectifier potassium (Kir) channels comprise a superfamily of potassium (K+) channels with unique structural and functional properties. Expressed in virtually all types of cells they are responsible for setting the resting membrane potential, controlling the excitation threshold and secreting K+ ions. All Kir channels present an inwardly rectifying current-voltage relation, meaning that at any given driving force the inward flow of K+ ions exceeds the outward flow for the opposite driving force. This inward-rectification is due to a voltage-dependent block of the channel pore by intracellular polyamines and magnesium. The present molecular-biophysical understanding of inward-rectification and its physiological consequences is the topic of this review. In addition to polyamines, Kir channels are gated by intracellular protons, G-proteins, ATP and phospholipids depending on the respective Kir subfamily as detailed in the following review articles.
Oliver
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Department of Physiology II, University of Tübingen, Germany.
Baukrowitz
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Fakler
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D000818:Animals; D003001:Cloning, Molecular; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects*; D017136:Ion Transport / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008958:Models, Molecular; D011073:Polyamines / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000145:classification / Q000187:drug effects* / Q000502:physiology; D024661:Potassium Channels, Inwardly Rectifying; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000378:metabolism
D011073:Polyamines; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011993:Recombinant Fusion Proteins; D011188:Potassium