Allosteric modulation of the human P-glycoprotein involves conformational changes mimicking catalytic transition intermediates

Archives of Biochemistry and Biophysics
Pratiti GhoshSaibal Dey

Abstract

The drug transport function of human P-glycoprotein (Pgp, ABCB1) can be inhibited by a number of pharmacological agents collectively referred to as modulators or reversing agents. In this study, we demonstrate that certain thioxanthene-based Pgp modulators with an allosteric mode of action induce a distinct conformational change in the cytosolic domain of Pgp, which alters susceptibility to proteolytic digestion. Both cis and trans-isomers of the Pgp modulator flupentixol confer considerable protection of an 80 kDa Pgp fragment against trypsin digestion, that is recognized by a polyclonal antibody specific for the NH(2)-terminal half to Pgp. The protection by flupentixol is abolished in the Pgp F983A mutant that is impaired in modulation by flupentixols, indicating involvement of the allosteric site in generating the conformational change. A similar protection to an 80 kDa fragment is conferred by ATP, its nonhydrolyzable analog ATPgammaS, and by trapping of ADP-vanadate at the catalytic domain, but not by transport substrate vinblastine or by the competitive modulator cyclosporin A, suggesting different outcomes from modulator interaction at the allosteric site and at the substrate site. In summary, we demonstrate that alloste...Continue Reading

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Citations

Jan 9, 2007·Pharmacology & Therapeutics·Christopher A McDevitt, Richard Callaghan
Jun 6, 2009·The FEBS Journal·Tomomi SatoHiroaki Kato
Sep 17, 2011·Biochemical Pharmacology·Annalisa NeriGiampietro Sgaragli
Jun 26, 2020·Frontiers in Oncology·Yena Cho, Yong Kee Kim

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