1jvm
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KCSA POTASSIUM CHANNEL WITH TBA (TETRABUTYLAMMONIUM) AND RUBIDIUM
OverviewOverview
The K+ selectivity filter catalyses the dehydration, transfer and, rehydration of a K+ ion in about ten nanoseconds. This physical process is, central to the production of electrical signals in biology. Here we show, how nearly diffusion-limited rates are achieved, by analysing ion, conduction and the corresponding crystallographic ion distribution in the, selectivity filter of the KcsA K+ channel. Measurements with K+ and its, slightly larger analogue, Rb+, lead us to conclude that the selectivity, filter usually contains two K+ ions separated by one water molecule. The, two ions move in a concerted fashion between two configurations, K+-water-K+-water (1,3 configuration) and water-K+-water-K+ (2,4, configuration), until a third ion enters, displacing the ion on the, opposite side of the queue. For K+, the energy difference between the 1,3, and 2,4 configurations is close to zero, the condition of maximum, conduction rate. The energetic balance between these configurations is a, clear example of evolutionary optimization of protein function.
About this StructureAbout this Structure
1JVM is a Single protein structure of sequence from Streptomyces lividans with RB and TBA as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Energetic optimization of ion conduction rate by the K+ selectivity filter., Morais-Cabral JH, Zhou Y, MacKinnon R, Nature. 2001 Nov 1;414(6859):37-42. PMID:11689935
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