Kinetics of endosomal pH evolution in Dictyostelium discoideum amoebae. Study by fluorescence spectroscopy. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Cell Science Année : 1993

Kinetics of endosomal pH evolution in Dictyostelium discoideum amoebae. Study by fluorescence spectroscopy.

Résumé

The evolution of endo-lysosomal pH in Dictyostelium discoideum amoebae was examined during fluid-phase endocytosis. Pulse-chase experiments were conducted in nutritive medium or in non-nutritive medium using fluorescein labelled dextran (FITC-dextran) as fluid-phase marker and pH probe. In both conditions, efflux kinetics were characterized by an extended lag phase lasting for 45-60 min and corresponding to intracellular transit of FITC-dextran cohort. During the chase period, endosomal pH decreased during approximately 20 min from extracellular pH down to pH 4.6-5.0, then, it increased within the next 20-40 min to reach pH 6.0-6.2. It was only at this stage that FITC-dextran was released back into the medium with pseudo first-order kinetics. A vacuolar H(+)-ATPase is involved in endosomal acidification as the acidification process was markedly reduced in mutant strain HGR8, partially defective in vacuolar H(+)-ATPase and in parent type strain AX2 by bafilomycin A1, a selective inhibitor of this enzyme. Our data suggest that endocytic cargo is channeled from endosomes to secondary lysosomes that are actively linked to the plasma membrane via recycling vesicles.

Domaines

Biophysique
Fichier non déposé

Dates et versions

hal-00247399 , version 1 (07-02-2008)

Identifiants

  • HAL Id : hal-00247399 , version 1
  • PUBMED : 7691851

Citer

L. Aubry, G. Klein, Jean-Louis Martiel, M. Satre. Kinetics of endosomal pH evolution in Dictyostelium discoideum amoebae. Study by fluorescence spectroscopy.. Journal of Cell Science, 1993, 105 ( Pt 3), pp.861-6. ⟨hal-00247399⟩
912 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More