Differential targeting of dense granule proteins in the parasitophorous vacuole of Toxoplasma gondii.
The biosynthesis and fate of 4 different dense granule proteins of Toxoplasma gondii were studied with 3 monoclonal antibodies raised against tachyzoites and 1 polyclonal antibody raised against a recombinant protein. These proteins have the following molecular weights: 27 kDa (GRA 1), 28 kDa (GRA 2), 30 kDa (GRA 3) and 40 kDa (GRA 4). All four proteins were found in dense granules by immunoelectron microscopy; in T. gondii-infected cells, they were found in the vacuolar network but, in addition, GRA 3 was also detected on the parasitophorous vacuole membrane. Therefore, dense granule contents undergo differential targeting when exocytosed in the parasitophorous vacuole. Metabolic labelling and immunoprecipitation showed that GRA 2 and GRA 3 were processed from lower molecular weight precursors, and that GRA 2 and GRA 4 incorporated [3H] glucosamine and are thus likely to be glycosylated.
Achbarou
A
A
Unité 42 INSERM, Villeneuve d'Ascq, France.
Mercereau-Puijalon
O
O
Sadak
A
A
Fortier
B
B
Leriche
M A
MA
Camus
D
D
Dubremetz
J F
JF
D000818:Animals; D015153:Blotting, Western; D005455:Fluorescent Antibody Technique; D016253:Microscopy, Immunoelectron; D008970:Molecular Weight; D011233:Precipitin Tests; D015800:Protozoan Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000737:chemistry; D014122:Toxoplasma / Q000737:chemistry* / Q000648:ultrastructure; D014617:Vacuoles / Q000737:chemistry*; D014709:Vero Cells
D015800:Protozoan Proteins