Abstract.
Multidrug resistance to anti-cancer drugs is a major medical problem. Resistance is manifested largely by the product of the human MDR1 gene, P-glycoprotein, an ABC transporter that is an integral membrane protein of 1280 amino acids arranged into two homologous halves, each comprising 6 putative transmembrane α-helices and an ATP binding domain. Despite the plethora of data from site-directed, scanning and domain replacement mutagenesis, epitope mapping and photoaffinity labeling, a clear structural model for P-glycoprotein remains largely elusive. In this report, we propose a new model for P-glycoprotein that is supported by the vast body of previous data. The model comprises 2 membrane-embedded 16-strand β-barrels, attached by short loops to two 6-helix bundles beneath each barrel. Each ATP binding domain contributes 2 β-strands and 1 α-helix to the structure. This model, together with an analysis of the amino acid sequence alignment of P-glycoprotein isoforms, is used to delineate drug binding and translocation sites. We show that the locations of these sites are consistent with mutational, kinetic and labeling data.
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Received: 18 February 1998/Revised: 2 September 1998
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Jones, P., George, A. A New Structural Model for P-Glycoprotein. J. Membrane Biol. 166, 133–147 (1998). https://doi.org/10.1007/s002329900455
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DOI: https://doi.org/10.1007/s002329900455