Differential targeting of dense granule proteins in the parasitophorous vacuole of Toxoplasma gondii

• Published in: Parasitology Vol. 103; p. 321
• Main Authors: Achbarou, A. (INSERM, Villeneuve of Ascq, France), Mercereau-Puijalon, O, Sadak, A, Fortier, B, Leriche, M.A, Camus, D, Dubremetz, J.F
• Format: Journal Article
• Language: English
• Published: England 01.12.1991
• Subjects: Animals; Blotting, Western; Fluorescent Antibody Technique; GRANULE; GRANULES; GRANULOS; HOST PARASITE RELATIONS; MEMBRANA; MEMBRANE; MEMBRANES; Microscopy, Immunoelectron; Molecular Weight; Precipitin Tests; PROTEIN SYNTHESIS; PROTEINAS; PROTEINE; PROTEINS; Protozoan Proteins - analysis; Protozoan Proteins - biosynthesis; Protozoan Proteins - chemistry; RELACIONES HUESPED PARASITO; RELATION HOTE PARASITE; SINTESIS DE PROTEINAS; SYNTHESE PROTEIQUE; TOXOPLASMA; Toxoplasma - chemistry; Toxoplasma - ultrastructure; VACUOLA; VACUOLAR NETWORK; VACUOLE; VACUOLES; Vacuoles - chemistry; Vero Cells
• ISSN: 0031-1820; 1469-8161
• DOI: 10.1017/S0031182000059837

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.