P-glycoprotein substrate binding domains are located at the transmembrane domain/transmembrane domain interfaces: A combined photoaffinity labeling-protein homology modeling approach
- Author(s)
- Karin Pleban, Stephan Kopp, Edina Csaszar, Michael Peer, Thomas Hrebicek, Andreas Rizzi, Gerhard Ecker, Peter Chiba
- Abstract
P-glycoprotein (P-gp) is an energy-dependent multidrug efflux pump conferring resistance to cancer chemotherapy. Characterization of the mechanism of drug transport at a molecular level represents an important prerequisite for the design of pump inhibitors, which resensitize cancer cells to standard chemotherapy. In addition, P-glycoprotein plays an important role for early absorption, distribution, metabolism, excretion, and toxicity profiling in drug development. A set of propafenonetype substrate photoaffinity ligands has been used in this study in conjunction with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to define the substrate binding domain(s) of P-gp in more detail. The highest labeling was observed in transmembrane segments 3, 5, 8, and 11. A homology model for P-gp was generated on the basis of the dimeric crystal structure of Vibrio cholerae MsbA, an essential lipid transporter. Thereafter, the labeling pattern was projected onto the 3D atomic-detail model of P-gp to allow a visualization of the binding domain(s). Labeling is predicted by the model to occur at the two transmembrane domain/transmembrane domain interfaces formed between the amino- and carboxyl-terminal half of P-gp. These interfaces are formed by transmembrane (TM) segments 3 and 11 on one hand and TM segments 5 and 8 on the other hand. Available data on LmrA and AcrB, two bacterial multidrug efflux pumps, suggest that binding at domain interfaces may be a general feature of polyspecific drug efflux pumps.
- Organisation(s)
- External organisation(s)
- Medizinische Universität Wien
- Journal
- Molecular Pharmacology
- Volume
- 67
- Pages
- 365-374
- No. of pages
- 10
- ISSN
- 0026-895X
- DOI
- https://doi.org/10.1124/mol.104.006973
- Publication date
- 2005
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 3012 Pharmacy, Pharmacology, Toxicology
- Sustainable Development Goals
- SDG 3 - Good Health and Well-being
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/e297fd93-0b65-4a75-a50b-934a39b5c18e