Abstract
Potassium channels can conduct passively K+ ions with rates of up to approximately 10(8) ions per second at physiological conditions, and they are selective to these species by a factor of 10(4) over Na+ ions. Ion conduction has been proposed to involve transitions between 2 main states, with 2 or 3 K+ ions occupying the selectivity filter separated by an intervening water molecule. The largest free energy barrier of such a process was reported to be of the order of 2-3 kcal mol(-1). Here, we present an alternative mechanism for conduction of K+ in potassium channels where site vacancies are involved, and we propose that coexistence of several ion permeation mechanisms is energetically possible. Conduction can be described as a more anarchic phenomenon than previously characterized by the concerted translocations of K+-water-K+.
| Original language | English |
|---|---|
| Pages (from-to) | 16074-7 |
| Number of pages | 4 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 106 |
| Issue number | 38 |
| DOIs | |
| Publication status | Published - 22 Sept 2009 |
Keywords
- Bacterial Proteins
- Binding Sites
- Computer Simulation
- Crystallography, X-Ray
- Ion Channel Gating
- Models, Molecular
- Potassium
- Potassium Channels
- Protein Conformation
- Protein Structure, Tertiary
- Thermodynamics
- Water