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Cooperative P‐glycoprotein mediated daunorubicin transport into DNA‐loaded plasma membrane vesicles
Author(s) -
Myriam Guiral,
Odile M. Viratelle,
Hans V. Westerhoff,
J. Lankelma
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)00447-1
Subject(s) - daunorubicin , p glycoprotein , vesicle , efflux , chemistry , membrane transport , membrane , mediated transport , transporter , biophysics , dna , quenching (fluorescence) , biochemistry , fluorescence , biology , multiple drug resistance , gene , immunology , leukemia , antibiotics , physics , quantum mechanics
Most of the multidrug resistant human tumor cell lines overexpress the MDR 1 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 K m of 1.5 ± 0.1 μM. This transport occured 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.