Interaction of organic chemicals with P-glycoprotein in the adrenal gland, kidney, and a multidrug-resistant KB cell

M. Ichikawa, A. Yoshimura, T. Sumizawa, N. Shudo, Y. Kuwazuru, T. Furukawa, S. Akiyama

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10 Citations (Scopus)


P-glycoprotein (P-gp) is thought to mediate the transport of anti-cancer drugs and to be responsible for the multidrug-resistant (MDR) phenotype in tumor cells. However, the function of P-gp in normal tissues is still not well understood. We present evidence indicating that the active efflux of several structurally unrelated organic compounds is mediated by P-gp in multidrug-resistant KB (KB-C2) cells and that these compounds interact with P-gp in the kidney and adrenal gland. The photoactive radioactive calcium channel blocker [3H]azidopine labels a protein of ~ 140 kDa in crude membrane fractions from human kidney and adrenal gland and a 130-kDa protein from bovine adrenal gland. These photolabeled proteins are immunoprecipitated with an anti-P-gp antibody. Photolabeling is inhibited by vinblastine, reserpine, and several other organic chemicals. These data indicate that the kidney and adrenal gland express P-gp (or a protein closely related to P-gp) that can interact with several organic compounds and that the P-gp expressed in these tissues has a drug-binding site similar to that of P-gp in KB-C2 cells. Our findings thus strongly support the hypothesis that P-gp can transport a wide variety of organic chemicals as well as anti-cancer drugs and that one of the physiological functions of Pgp is the excretion of certain classes of organic compounds.

Original languageEnglish
Pages (from-to)903-908
Number of pages6
JournalJournal of Biological Chemistry
Issue number2
Publication statusPublished - 1991
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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