The Role of the Lipid Bilayer in P-glycoprotein Drug Binding, Transport and Catalytic Functions

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The Role of the Lipid Bilayer in P-glycoprotein Drug Binding, Transport and Catalytic Functions

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Title: The Role of the Lipid Bilayer in P-glycoprotein Drug Binding, Transport and Catalytic Functions
Author: Clay, Adam Thomas
Department: Department of Molecular and Cellular Biology
Program: Biophysics
Advisor: Frances, Sharom
Abstract: The ABC protein P-glycoprotein (Pgp, ABCB1) transports many structurally diverse substrates from the lipid bilayer. Previous studies demonstrated the importance of the membrane environment, but few have quantified these effects. In the present work, purified Pgp reconstituted into defined lipid systems was employed. Drug binding affinities were determined using Trp quenching, and drug-lipid partitioning by equilibrium dialysis. Pgp bound substrates from the bilayer with affinities in the millimolar range; both drug-Pgp and drug-lipid interactions were important. The kinetics of Pgp-mediated drug transport were sensitive to drug structure and lipid environment. The rate of transport is proposed to depend on the affinity of Pgp for substrate and conformational changes. The lipid bilayer affected the stability of Pgp catalytic activity which provided evidence for distinct basal and drug-stimulated ATPase cycles. Overall, the lipid environment had pronounced effects on Pgp-mediated drug binding, transport and catalytic functions.
URI: http://hdl.handle.net/10214/3196
Date: 2011-12-16


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