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Detection and Localization of a Ca2+-ATPase Activity in Toxoplasma gondii.

2001; Japan Society of Cell Biology; Volume: 26; Issue: 1 Linguagem: Inglês

10.1247/csf.26.49

1347-3700

André Bouchot, Jean-David Jaillet, Annie Bonhomme, Nathalie Pezzella-D' Alessandro, Patrice Laquerrière, Laurence Kilian, Henriette Burlet, Jorge Enrique Gómez‐Marín, M Pluot, P. Bonhomme, Jean‐Michel Pinon,

Synthesis and Characterization of Heterocyclic Compounds

Toxoplasma gondii, the agent causing toxoplasmosis, is an obligate intracellular protozoan parasite. A calcium signal appears to be essential for intracellular transduction during the active process of host cell invasion. We have looked for a Ca2+-transport ATPase in tachyzoites and found Ca2+-ATPase activity (11-22 nmol Pi liberated/mg protein/min) in the tachyzoite membrane fraction. This ATP-dependent activity was stimulated by Ca2+ and Mg2+ ions and by calmodulin, and was inhibited by pump inhibitors (sodium orthovanadate or thapsigargin). We used cytochemistry and X-ray microanalysis of cerium phosphate precipitates and immunolabelling to find the Ca2+, Mg2+-ATPase. It was located mainly in the membrane complex, the conoid, nucleus, secretory organelles (rhoptries, dense granules) and in vesicles with a high calcium concentration. Thus, Toxoplasma gondii possesses Ca2+-pump ATPase (Ca2+, Mg2+-ATPase) as do eukaryotic cells.