Phosphatidylcholine translocase: a physiological role for the mdr2 gene

Cell. 1994 Jul 1;77(7):1071-81. doi: 10.1016/0092-8674(94)90446-4.


P-glycoproteins (P-gps) encoded by the mouse mdr2 and mdr3 genes were expressed in secretory vesicles (SVs) from the yeast mutant sec6-4, and their capacity to function as a lipid translocase/flippase was tested. An assay that uses a fluorescent phosphatidylcholine (PC) analog was developed to quantitate asymmetric lipid distribution in the outer and inner leaflets of the lipid bilayer of these vesicles. Mdr2 expression in SVs caused a time- and temperature-dependent enhancement of PC translocation to the inner leaflet of the membrane. The Mdr2-mediated effect was specific since expression of Mdr3 in these vesicles was without effect on the membrane distribution of PC. Increased Mdr2-mediated PC translocation was strictly ATP and Mg2+ dependent, was abrogated by the ATPase inhibitor vanadate and the P-gp modulator verapamil, but was insensitive to the presence of excess of the multidrug resistance drugs colchicine and vinblastine.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Animals
  • Biological Transport
  • Carrier Proteins / metabolism*
  • Cytoplasmic Granules / metabolism
  • In Vitro Techniques
  • Lipid Bilayers
  • Membrane Glycoproteins / metabolism*
  • Membrane Lipids / metabolism*
  • Mice
  • Phosphatidylcholines / metabolism*
  • Recombinant Proteins
  • Saccharomyces cerevisiae


  • ATP Binding Cassette Transporter, Subfamily B, Member 1
  • Carrier Proteins
  • Lipid Bilayers
  • Membrane Glycoproteins
  • Membrane Lipids
  • Phosphatidylcholines
  • Recombinant Proteins