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2itc
From Proteopedia
| 2itc, resolution 3.20Å () | |||||||||
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| Sites: | and | ||||||||
| Ligands: | |||||||||
| Gene: | kcsA, skc1 (Streptomyces lividans) | ||||||||
| Related: | 2itd, 2nlj | ||||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||||
Contents |
Potassium Channel KcsA-Fab complex in Sodium Chloride
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.
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
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
2itc is a 3 chain structure of Monoclonal Antibody and Potassium Channel with sequence from Mus musculus and Streptomyces lividans. Full crystallographic information is available from OCA.
See Also
Reference
- Lockless SW, Zhou M, MacKinnon R. Structural and thermodynamic properties of selective ion binding in a K+ channel. PLoS Biol. 2007 May;5(5):e121. PMID:17472437 doi:10.1371/journal.pbio.0050121
