Aminopeptidase N/CD13 is associated with raft membrane microdomains in monocytes

Biochem Biophys Res Commun. 2000 Mar 5;269(1):143-8. doi: 10.1006/bbrc.2000.2271.

Abstract

Ectopeptidases play important roles in cell activation, proliferation, and communication. Human monocytic cells express considerable amounts of aminopeptidase N/CD13, a transmembrane protein previously proposed to play a role in the regulation of neuropeptides and chemotactic mediators as well as in adhesion and cell-cell interactions. Here, we report for the first time that aminopeptidase N/CD13 in monocytes is partially localized in detergent-insoluble membrane microdomains enriched in cholesterol, glycolipids, and glycosylphosphoinositol-anchored proteins, referred to as "rafts." Raft fractions of monocytes were characterized by the presence of GM1 ganglioside as raft marker molecule and by the high level of tyrosine-phosphorylated proteins. Furthermore, similar to polarized cells, rafts in monocytic cells lack Na(+), K(+)-ATPase. Cholesterol depletion of monocytes by methyl-beta-cyclodextrin greatly reduces raft localization of aminopeptidase N/CD13 without affecting ala-p-nitroanilide cleaving activity of cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CD13 Antigens / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / immunology*
  • Cell Membrane / metabolism*
  • Cholesterol / metabolism
  • Cyclodextrins / pharmacology
  • Detergents
  • G(M1) Ganglioside / metabolism
  • Humans
  • Membrane Lipids / metabolism
  • Membrane Proteins / metabolism
  • Microscopy, Confocal
  • Monocytes / drug effects
  • Monocytes / immunology*
  • Monocytes / metabolism*
  • Signal Transduction
  • Solubility
  • U937 Cells
  • beta-Cyclodextrins*

Substances

  • Cyclodextrins
  • Detergents
  • Membrane Lipids
  • Membrane Proteins
  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • G(M1) Ganglioside
  • Cholesterol
  • CD13 Antigens