Kinetics of endosomal pH evolution in Dictyostelium discoideum amoebae. Study by fluorescence spectroscopy. - Archive ouverte HAL Access content directly
Journal Articles Journal of Cell Science Year : 1993

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

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Abstract

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.
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Dates and versions

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

Identifiers

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

Cite

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⟩
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