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  Effects of lipid structure on the state of aggregation of potassium channel KcsA.

Bolivar, J. H., East, J. M., Marsh, D., & Lee, A. G. (2012). Effects of lipid structure on the state of aggregation of potassium channel KcsA. Biochemistry, 51(30), 6010-6016. doi:10.1021/bi3006253.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-000E-ED00-8 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0027-C84B-2
Genre: Journal Article

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1711634.pdf (Publisher version), 304KB
 
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http://pubs.acs.org/doi/ipdf/10.1021/bi3006253 (Publisher version)
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 Creators:
Bolivar, J. H., Author
East, J. M., Author
Marsh, D.1, Author              
Lee, A. G., Author
Affiliations:
1Emeritus Group of Spectroscopy and Photochemical Kinetics, MPI for Biophysical Chemistry, Max Planck Society, ou_578625              

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 Abstract: The state of aggregation of potassium channel KcsA was determined as a function of lipid:protein molar ratio in bilayer membranes of the zwitterionic lipid phosphatidylcholine (PC) and of the anionic lipid phosphatidylglycerol (PG). EPR (electron paramagnetic resonance) with spin-labeled phospholipids was used to determine the number of motionally restricted lipids per KcsA tetramer. Unexpectedly, this number decreased with a decreasing lipid:KcsA tetramer molar ratio in the range of 88:1 to 30:1, consistent with sharing of annular lipid shells and KcsA–KcsA contact at high mole fractions of protein. Fluorescence quenching experiments with brominated phospholipids showed a decrease in fluorescence quenching at low lipid:KcsA tetramer mole ratios, also consistent with KcsA–KcsA contact at high mole fractions of protein. The effects of low mole ratios of lipid seen in EPR and fluorescence quenching experiments were more marked in bilayers of PC than in bilayers of PG, suggesting stronger association of PG than PC with KcsA. This was confirmed by direct measurement of lipid association constants using spin-labeled phospholipids, showing higher association constants for all anionic lipids than for PC. The results show that the probability of contacts between KcsA tetramers will be very low at lipid:protein molar ratios that are typical of native biological membranes.

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Language(s): eng - English
 Dates: 2012-07-042012
 Publication Status: Published in print
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 Rev. Method: Peer
 Identifiers: DOI: 10.1021/bi3006253
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Title: Biochemistry
Source Genre: Journal
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Pages: - Volume / Issue: 51 (30) Sequence Number: - Start / End Page: 6010 - 6016 Identifier: -