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Expression of P-glycoprotein, the product of the MDR1 gene, confers multidrug resistance on cell lines and human tumours (reviewed in refs 1,2). P-glycoprotein (relative molecular mass 170,000) is an ATP-dependent, active transporter which pumps hydrophobic drugs out of cells, but its normal physiological role is unknown. It is a member of the ABC (ATP-binding cassette) superfamily of transporters, which includes many bacterial transport systems, the putative peptide transporter from the major histocompatibility locus, and the product of the cystic fibrosis gene (the cystic fibrosis transmembrane regulator, CFTR). CFTR is located in the apical membranes of many secretory epithelia and is associated with a cyclic AMP-regulated chloride channel. At least two other chloride channels are present in epithelial cells, regulated by cell volume and by intracellular Ca2+, respectively. Because of the structural and sequence similarities between P-glycoprotein and CFTR, and because P-glycoprotein is abundant in many secretory epithelia, we examined whether P-glycoprotein might be associated with one or other of these channels. We report here that expression of P-glycoprotein generates volume-regulated, ATP-dependent, chloride-selective channels, with properties similar to channels characterized previously in epithelial cells.

Original publication

DOI

10.1038/355830a0

Type

Journal article

Journal

Nature

Publication Date

27/02/1992

Volume

355

Pages

830 - 833

Keywords

3T3 Cells, ATP Binding Cassette Transporter, Subfamily B, Member 1, Animals, Chloride Channels, Chlorides, Colforsin, Drug Resistance, Genetic Vectors, Humans, Ion Channels, Kinetics, Membrane Glycoproteins, Membrane Potentials, Membrane Proteins, Mice, Molecular Weight, Transfection, Vaccinia virus