scholarly journals Selective Inhibition of Active Uptake of Sucrose into Plasma Membrane Vesicles by Polyclonal Sera Directed against a 42 Kilodalton Plasma Membrane Polypeptide

1992 ◽  
Vol 98 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Olivier Gallet ◽  
Rémi Lemoine ◽  
Cécile Gaillard ◽  
Christer Larsson ◽  
Serge Delrot
Keyword(s):  
Plasma Membrane ◽  
Membrane Vesicles ◽  
Selective Inhibition ◽  
Plasma Membrane Vesicles ◽  
Active Uptake

scholarly journals A calmodulin-stimulated Ca2+ pump in plasma-membrane vesicles from Trypanosoma brucei; selective inhibition by pentamidine

1993 ◽  
Vol 296 (3) ◽  
pp. 759-763 ◽  
Author(s):  
G Benaim ◽  
C Lopez-Estraño ◽  
R Docampo ◽  
S N J Moreno
Keyword(s):  
Plasma Membrane ◽  
Trypanosoma Brucei ◽  
Membrane Vesicles ◽  
Selective Inhibition ◽  
Fine Tuning ◽  
Ionophore A23187 ◽  
Plasma Membrane Vesicles ◽  
Calmodulin Antagonist ◽  
Stimulation Of

Despite previous reports [McLaughlin (1985) Mol. Biochem. Parasitol. 15, 189-201; Ghosh, Ray, Sarkar and Bhaduri (1990) J. Biol. Chem. 265, 11345-11351; Mazumder, Mukherjee, Ghosh, Ray and Bhaduri (1992) J. Biol. Chem. 267, 18440-18446] that the plasma membrane of different trypanosomatids only contains Ca(2+)-ATPase that does not show any demonstrable dependence on Mg2+, a high-affinity (Ca(2+)-Mg2+)-ATPase was demonstrated in the plasma membrane of Trypanosoma brucei. The enzyme became saturated with micromolar amounts of Ca2+, reaching a Vmax. of 3.45 +/- 0.66 nmol of ATP/min per mg of protein. The Km,app. for Ca2+ was 0.52 +/- 0.03 microM. This was decreased to 0.23 +/- 0.05 microM, and the Vmax. was increased to 6.36 +/- 0.22 nmol of ATP/min per mg of protein (about 85%), when calmodulin was present. T. brucei plasma-membrane vesicles accumulated Ca2+ on addition of ATP only when Mg2+ was present, and released it to addition of the Ca2+ ionophore A23187. In addition, this Ca2+ transport was stimulated by calmodulin. Addition of NaCl to Ca(2+)-loaded T. brucei plasma-membrane vesicles did not result in Ca2+ release, thus suggesting the absence of a Na+/Ca2+ exchanger in these parasites. Therefore the (Ca(2+)-Mg2+)-ATPase would be the only mechanism so far described that is responsible for the long-term fine tuning of the intracellular Ca2+ concentration of these parasites. The trypanocidal drug pentamidine inhibited the T. brucei plasma-membrane (Ca(2+)-Mg2+)-ATPase and Ca2+ transport at concentrations that had no effect on the Ca(2+)-ATPase activity of human or pig erythrocytes. In this latter case, pentamidine behaved as a weak calmodulin antagonist, since it inhibited the stimulation of the erythrocyte Ca(2+)-ATPase by calmodulin.

Calcium efflux of plasma membrane vesicles exposed to ELF magnetic fields-test of a nuclear magnetic resonance interaction model

2012 ◽  
Vol 33 (7) ◽  
pp. 535-542 ◽  
Author(s):  
Wenjun J. Sun ◽  
Mehri Kaviani Mogadam ◽  
Marianne Sommarin ◽  
Henrietta Nittby ◽  
Leif G. Salford ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Plasma Membrane ◽  
Magnetic Resonance ◽  
Magnetic Fields ◽  
Interaction Model ◽  
Membrane Vesicles ◽  
Resonance Interaction ◽  
Calcium Efflux ◽  
Plasma Membrane Vesicles ◽  
Nuclear Magnetic
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