Cooperative P‐glycoprotein mediated daunorubicin transport into DNA‐loaded plasma membrane vesicles
- 13 June 1994
- journal article
- Published by Wiley in FEBS Letters
- Vol. 346 (2-3) , 141-145
- https://doi.org/10.1016/0014-5793(94)00447-1
Abstract
Most of the multidrug resistant human tumor cell lines overexpress the MDR1 gene product P-glycoprotein (P-gp) which is believed to function as an energy-dependent drug efflux pump. Here we describe a novel method that allows the kinetic characterization of P-gp-mediated active drug transport. This method is based on the fluorescence quenching of anthracyclines transported into DNA-loaded plasma membrane vesicles. The uptake of daunorubicin (DNR) into the plasma membrane vesicles was saturable in terms of the extravesicular DNR concentration with a Km of 1.5 +/- 0.1 microM. This transport occurred by a cooperative process with a Hill coefficient close to 2 for DNR. A model is discussed in which P-gp pumps two molecules of drug per turnover.Keywords
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