The product of the ABC half-transporter gene ABCG2 (BCRP/MXR/ABCP) is expressed in the plasma membrane

Biochem Biophys Res Commun. 2000 Apr 29;271(1):42-6. doi: 10.1006/bbrc.2000.2590.


The products of the ABC gene family can be generally classified as either full-transporters of half-transporters. Full-transporters are expressed in the plasma membrane, whereas half-transporters are usually found in intracellular membranes. Recently, an ABC half-transporter, the ABCG2 gene product Breast Cancer/Mitoxantrone Resistance Protein (BCRP/MXR), has been shown to cause mitoxantrone and topotecan resistance. The purpose of this study was to determine the expression and the intracellular localization of this protein in various drug-resistant cell lines. BCRP/MXR expression was determined by Western blot and immunohistochemistry. This protein is highly overexpressed in several drug-resistant cell lines and localizes predominantly to the plasma membrane, instead of to intracellular membranes as seen with all other known half-transporters. Therefore, BCRP/MXR is unique among the ABC half-transporters by being localized to the plasma membrane.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • ATP-Binding Cassette Transporters / biosynthesis*
  • Blotting, Western
  • Breast Neoplasms / metabolism
  • Cell Membrane / metabolism*
  • Colonic Neoplasms / metabolism
  • Drug Resistance, Neoplasm
  • Humans
  • Immunohistochemistry
  • Microscopy, Fluorescence
  • Tumor Cells, Cultured


  • ATP-Binding Cassette Transporters