Bouchot A, Jaillet JD, Bonhomme A, Alessandro NP, Laquerriere P, Kilian L, Burlet H, Gomez-Marin JE, Pluot M, Bonhomme P, Pinon JM. Detection and localization of a Ca2+-ATPase activity in Toxoplasma gondii.
Cell Struct Funct 2001;
26:49-60. [PMID:
11345503 DOI:
10.1247/csf.26.49]
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Abstract
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.
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