The membrane potential of the intraerythrocytic malaria parasite Plasmodium falciparum

Allen, Richard J. W. and Kirk, Kiaran (2004) The membrane potential of the intraerythrocytic malaria parasite Plasmodium falciparum. The Journal of Biological Chemistry, 279 12: 11264-11272. doi:10.1074/jbc.M311110200

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Author Allen, Richard J. W.
Kirk, Kiaran
Title The membrane potential of the intraerythrocytic malaria parasite Plasmodium falciparum
Journal name The Journal of Biological Chemistry   Check publisher's open access policy
ISSN 0021-9258
Publication date 2004-03-19
Sub-type Article (original research)
DOI 10.1074/jbc.M311110200
Open Access Status File (Publisher version)
Volume 279
Issue 12
Start page 11264
End page 11272
Total pages 9
Place of publication United States
Publisher American Society for Biochemistry and Molecular Biology, Inc.
Language eng
Formatted abstract
The membrane potential (ΔΦ) of the mature asexual form of the human malaria parasite, Plasmodium falciparum, isolated from its host erythrocyte using a saponin permeabilization technique, was investigated using both the radiolabeled ΔΦ indicator tetraphenylphosphonium ([ 3H]TPP+) and the fluorescent ΔΦ indicator DiBAC4(3) (bis-oxonol). For isolated parasites suspended in a high Na+, low K+ solution, ΔΦ was estimated from the measured distribution of [3H]TPP+ to be - 95 ± 2 mV. ΔΦ was reduced by the specific V-type H+ pump inhibitor bafilomycin A1, by the H+ ionophore CCCP, and by glucose deprivation. Acidification of the parasite cytosol (induced by the addition of lactate) resulted in a transient hyperpolarization, whereas a cytosolic alkalinization (induced by the addition of NH4+) resulted in a transient depolarization. A decrease in the extracellular pH resulted in a membrane depolarization, whereas an increase in the extracellular pH resulted in a membrane hyperpolarization. The parasite plasma membrane depolarized in response to an increase in the extracellular K+ concentration and hyperpolarized in response to a decrease in the extracellular K+ concentration and to the addition of the K + channel blockers Ba2+ or Cs+ to the suspending medium. The data are consistent with ΔΦ of the intraerythrocytic P. falciparum trophozoite being due to the electrogenic extrusion of H+ via the V-type H+ pump at the parasite surface. The current associated with the efflux of H+ is countered, in part, by the influx of K+ via Ba2+- and Cs +-sensitive K+ channels in the parasite plasma membrane.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
Collection: Institute for Molecular Bioscience - Publications
 
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Created: Thu, 07 Apr 2011, 14:39:23 EST by Susan Allen on behalf of Institute for Molecular Bioscience