Wheat germ agglutinin is selectively transported to multivesicular bodies

Eur J Cell Biol. 1991 Jun;55(1):83-93.

Abstract

Colloidal iron dextran particles bearing wheat germ agglutinin (WGA/FeDex) were bound by glycoconjugates expressed at the surface of HepG2 cells. Bound WGA/FeDex was internalized when cells were incubated at 37 degrees C and accumulated in intracellular structures which have the same buoyant density as the plasma membrane when examined on Percoll density gradients. The intracellular structures containing WGA/FeDex were identified as multivesicular bodies (MVB) by transmission electron microscopy. WGA/FeDex was not transported to lysosomes nor did it interfere with uptake and transport of GalBSA to lysosomes by the asialoglycoprotein receptor. WGA/FeDex was seen predominantly in non-coated invaginations at the cell surface, suggesting it may enter cells at a different site than GalBSA/FeDex. Highly enriched plasma membranes and MVBs containing superparamagnetic [125I]WGA/FeDex particles were prepared by high gradient magnetic affinity chromatography (HIMAC). Plasma membranes prepared by HIMAC were enriched 30-fold for [125I]WGA/FeDex, 15-fold for alkaline phosphodiesterase I, and 9-fold for galactosyltransferase relative to the crude post-nuclear homogenate and consisted entirely of plasmalemmal sheets. Intracellular structures containing WGA/FeDex were enriched 35-fold for [125I]WGA/FeDex, 10-fold for alkaline phosphodiesterase I, and 10-fold for galactosyltransferase but did not contain lysosomal beta-galactosidase. WGA/FeDex has a different ultimate destination in HepG2 cells than ligands internalized by the asialoglycoprotein receptor and can be used to obtain highly enriched plasma membranes and MVBs from cultured cells.

Publication types

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

MeSH terms

  • Animals
  • Binding Sites
  • Biological Transport
  • Cell Fractionation / methods
  • Cell Line
  • Cell Membrane / metabolism
  • Chromatography, Affinity / methods
  • Endosomes / metabolism*
  • Glycoconjugates / metabolism*
  • Humans
  • Iron-Dextran Complex / metabolism*
  • Ligands
  • Lysosomes / metabolism
  • Microscopy, Electron
  • Temperature
  • Tumor Cells, Cultured
  • Wheat Germ Agglutinins / metabolism*

Substances

  • Glycoconjugates
  • Ligands
  • Wheat Germ Agglutinins
  • Iron-Dextran Complex