2itc
From Proteopedia
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==Overview== | ==Overview== | ||
| - | Thermodynamic measurements of ion binding to the Streptomyces lividans | + | 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. |
==About this Structure== | ==About this Structure== | ||
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[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Streptomyces lividans]] | [[Category: Streptomyces lividans]] | ||
| - | [[Category: Lockless, S | + | [[Category: Lockless, S W.]] |
[[Category: MacKinnon, R.]] | [[Category: MacKinnon, R.]] | ||
[[Category: Zhou, M.]] | [[Category: Zhou, M.]] | ||
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[[Category: voltage-gated channel]] | [[Category: voltage-gated channel]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 17:55:44 2008'' |
Revision as of 15:55, 21 February 2008
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Potassium Channel KcsA-Fab complex in Sodium Chloride
Overview
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.
About this Structure
2ITC is a Single protein structure of sequence from Mus musculus and Streptomyces lividans with as ligand. Full crystallographic information is available from OCA.
Reference
Structural and thermodynamic properties of selective ion binding in a K+ channel., Lockless SW, Zhou M, MacKinnon R, PLoS Biol. 2007 May;5(5):e121. PMID:17472437
Page seeded by OCA on Thu Feb 21 17:55:44 2008
