Epitopes described in "Structural and thermodynamic properties of selective ion binding in a K+ channel."

Article Authors:Steve W Lockless; Ming Zhou; Roderick MacKinnon
Article Title:Structural and thermodynamic properties of selective ion binding in a K+ channel.
Reference Detail
Reference ID:1019327
Abstract:Thermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K(+), Rb(+), Cs(+), and Ba(2+)) bound and not with smaller ions (Na(+), Mg(2+), and Ca(2+)). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 A from the ions. We conclude that ion selectivity in a K(+) channel is a property of size-matched ion binding sites created by the protein structure.
Affiliations:Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, New York, United States of America.
Reference Type:Literature
PubMed ID:17472437
Journal:PLoS Biol
Journal Volume:5
Article Pages:e121
Journal ISSN:1545-7885
Article Chemical List:Bacterial Proteins;Cations;Potassium Channels;prokaryotic potassium channel;Potassium Chloride;Sodium Chloride
Article MeSH List:Bacterial Proteins(chemistry; metabolism); Calorimetry; Cations(metabolism); Crystallography, X-Ray; Models, Molecular; Potassium Channels(chemistry; metabolism); Potassium Chloride; Protein Conformation; Sodium Chloride; Streptomyces lividans(metabolism); Thermodynamics
Curation Last Updated:2015-06-05 02:04:12