ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa

version 3 (curated until May 28, 2011)

Toxoplasma gondii sporozoites form a transient parasitophorous vacuole that is impermeable and contains only a subset of dense-granule proteins.

Tilley, M., Fichera, M. E., Jerome, M. E., Roos, D. S., White, M. W. (1997 Nov, Infect Immun)

Toxoplasma gondii sporozoites form two parasitophorous vacuoles during development within host cells, the first (PV1) during host cell invasion and the second (PV2) 18 to 24 h postinoculation. PV1 is structurally distinctive due to its large size, yet it lacks a tubulovesicular network (C. A. Speer, M. Tilley, M. Temple, J. A. Blixt, J. P. Dubey, and M. W. White, Mol. Biochem. Parasitol. 75:75-86, 1995). Confirming the finding that sporozoites have a different electron-dense-granule composition, we have now found that sporozoites within oocysts lack the mRNAs encoding the 5' nucleoside triphosphate hydrolases (NTPase). NTPase first appears 12 h postinfection. Other tachyzoite dense-granule proteins, GRA1, GRA2, GRA4, GRA5, and GRA6, were detected in oocyst extracts, and antibodies against these proteins stained granules in the sporozoite cytoplasm. In contrast to tachyzoite invasion of host cells, however, sporozoites did not exocytose the dense-granule proteins GRA1, GRA2, or GRA4 during PV1 formation. Even after NTPase induction, these proteins were retained within cytoplasmic granules rather than being secreted into PV1. Only GRA5 was secreted by the sporozoite during host cell invasion, becoming associated with the membrane surrounding PV1. Microinjection of sporozoite-infected cells with fluorescent dyes showed that PV1 is impermeable to fluorescent dyes with molecular masses as small as 330 Da, indicating that PV1 lacks channels through which molecules can pass from the host cytoplasm into the vacuole. By contrast, lucifer yellow rapidly diffused into PV2, demonstrating the presence of molecular channels. These studies indicate that PV1 and PV2 are morphologically, immunologically, and functionally distinct, and that PV2 appears to be identical to the tachyzoite vacuole. The inaccessibility of PV1 to host cell nutrients may explain why parasite replication does not occur in this vacuole.

PubMed: 9353039, full text

Localisation information

TGME49_070250 (GRA1) dense granule protein 1 / major antigenp24

Experimental localisation: not parasitophorous vacuole during sporozoite parasitophorous vacuole 1
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "While sporozoites inhabited the distinctive PV1, the staining of anti-GRA1, -GRA2, and -GRA4 antibodies was confined to dense granules within the sporozoite cytoplasm and no staining was observed outside of the parasite itself"
  • Microscopy type: Light
  • Microscopy method: antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: not PV during sporozoite parasitophorous vacuole 1

TGME49_027620 (GRA2) 28 kDa antigen

Experimental localisation: not parasitophorous vacuole during sporozoite parasitophorous vacuole 1
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "While sporozoites inhabited the distinctive PV1, the staining of anti-GRA1, -GRA2, and -GRA4 antibodies was confined to dense granules within the sporozoite cytoplasm and no staining was observed outside of the parasite itself"
  • Microscopy type: Light
  • Microscopy method: antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: not PV during sporozoite parasitophorous vacuole 1

TGME49_110780 (GRA4) hypothetical protein

Experimental localisation: not parasitophorous vacuole during sporozoite parasitophorous vacuole 1
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "While sporozoites inhabited the distinctive PV1, the staining of anti-GRA1, -GRA2, and -GRA4 antibodies was confined to dense granules within the sporozoite cytoplasm and no staining was observed outside of the parasite itself"
  • Microscopy type: Light
  • Microscopy method: antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: not PV during sporozoite parasitophorous vacuole 1

TGME49_086450 (GRA5) dense granule protein 5 precursor

Experimental localisation: parasitophorous vacuole membrane during sporozoite invasion, dense granule during sporozoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "GRA5 was secreted by the sporozoite during host cell invasion, becoming associated with the membrane surrounding PV1"
  • Microscopy type: Light
  • Microscopy method: antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: PVM during sporozoite invasion, dense granule during sporozoite

TGME49_077240 (NTPase, NTP1) nucleoside-triphosphatase I

Experimental localisation: not sporozoite 2 hours post inoculation, not sporozoite 6 hours post inoculation, dense granule during sporozoite 12 hours post inoculation, dense granule during sporozoite 18 hours post inoculation
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "NTPase is first detected as intracellular granular staining +/-12 h postinfection and is only secreted in PV2, not PV1."
  • Microscopy type: Light
  • Microscopy method: antibody directly to protein
  • Strain: VEG
  • Gene model mapping comments: inferred from another publication
  • Localisation record: not during sporozoite 2 hours post inoculation, not during sporozoite 6 hours post inoculation, dense granule during sporozoite 12 hours post inoculation, dense granule during sporozoite 18 hours post inoculation