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Crystallographic Study of the Tetrabutylammonium Block to the KcsA K(+) Channel. Parmvir Singh 2/17/10. Background. KcsA is isolated from Streptomyces lividans Regulate membrane excitability (maintain resting potential) 4 identical subunits Each subunit is 2 alpha- helices
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Crystallographic Study of the Tetrabutylammonium Block to the KcsA K(+) Channel Parmvir Singh 2/17/10
Background • KcsA is isolated from Streptomyces lividans • Regulate membrane excitability (maintain resting potential) • 4 identical subunits • Each subunit is 2 alpha- helices • Polar region= selectivity filter signature sequence
Asymmetric Unit of the K+ Channel Complex with TBA K+= Purple Tetrabutyl ammonium= orange Do quaternary ammonium ions block K+ channel pores? Do they cause a conformational change of the K+ selectivity filter?
Biological Assembly of the KcsA K+ Channel Conclusion?
References • http://www.ks.uiuc.edu/Research/smd_imd/kcsa/ • http://www.rcsb.org/pdb/explore/explore.do?structureId=2HVK