Structural and thermodynamic properties of selective ion binding in a K+ channel
2007
How Potassium Channels Selectively Bind Ions
publication
Evidence: high
Author Information
Author(s): Steve W Lockless, Ming Zhou, Roderick MacKinnon
Primary Institution: The Rockefeller University
Hypothesis
How does the K+ channel discriminate between K+ and Na+ ions?
Conclusion
The study concludes that ion selectivity in a K+ channel is determined by the channel's recognition of ion size rather than charge density.
Supporting Evidence
- The K+ channel recognizes an ion's size rather than its electric field strength.
- Binding of larger ions like K+, Rb+, and Cs+ is associated with a conformational change in the channel.
- Smaller ions like Na+ do not bind effectively and do not induce the necessary conformational change.
Takeaway
Potassium channels are like special doors that only let in the right-sized keys (ions) and keep the wrong ones out.
Methodology
The study used isothermal titration calorimetry and x-ray crystallography to measure ion binding and determine the structures of the K+ channel.
Digital Object Identifier (DOI)
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