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

version 3 (curated until May 28, 2011)

Toxoplasma gondii: redistribution of tachyzoite surface protein during host cell invasion and intracellular development.

Grimwood, J., Smith, J. E. (1995, Parasitol Res)

Immunoperoxidase localisation of antigen at the electron microscope level confirms that parasite surface proteins, in association with membrane, are shed from the surface of the zoite on invasion, while varying amounts are also internalised. SAG 1 is stable on intracellular zoites for up to 48 h, although new protein is also synthesised. SAG1 is present on the surface of daughter zoites and is found throughout the infected cell in distinct vacuoles; these vacuoles represent either direct extensions of the parasitophorous vacuole or true export of parasite surface material. Conflicting reports exist concerning the presence of SAG1 on the developing intraphagosomal membrane (IPM) network immediately post-invasion (Sibley et al. 1986; Dubremetz et al. 1993). It is not known whether the molecule continues to be expressed during intracellular development. The current study follows the fate of SAG1 during invasion and over the first 48 h of parasite multiplication within the host cell, using pre- and postinvasion labeling techniques at the electron microscope level.

PubMed: 8570580, full text

Localisation information

TGME49_033460 (SAG1, SRS29B, P30/SAG1, BSR4, P30) SRS29B (= SAG1, P30)

Experimental localisation: parasite plasma membrane during extracellular tachyzoite, parasite plasma membrane during after tachyzoite invasion, vesicle budding off zoite posterior during after tachyzoite invasion
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "immunoperoxidase detection of the major surface proteins SAG1 and SAG2 revealed that they were distributed uniformly on the surface of extracellular tachyzoites. During invasion of the host cell the majority of the surface label failed to pass throught the tight junction. The label appeared to remain associated with membrane accumulating at the posterior of the zoite, where it was shed in the form of vesicles. This pattern of redistribution was observed with both surface molecules (Figs. 1, 4). However, in some in- stances, shedding of the surface coat was not complete and varying amounts of label were internalised and re- mained on membrane associated with or adjacent to the parasite surface "
  • Microscopy type: EM
  • Microscopy method: Monoclonal antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: surface during extracellular tachyzoite, some parasite plasma membrane during after tachyzoite invasion, vesicles budding off zoite posterior during after tachyzoite invasion

TGME49_071050 (SAG2, P22) SRS34A (= SAG2A, P22)

Experimental localisation: parasite plasma membrane during extracellular tachyzoite, parasite plasma membrane during intracellular tachyzoite, parasite plasma membrane during after tachyzoite invasion, vesicle budding off zoite posterior during after tachyzoite invasion
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "immunoperoxidase detection of the major surface proteins SAG1 and SAG2 revealed that they were distributed uniformly on the surface of extracellular tachyzoites. During invasion of the host cell the majority of the surface label failed to pass throught the tight junction. The label appeared to remain associated with membrane accumulating at the posterior of the zoite, where it was shed in the form of vesicles. This pattern of redistribution was observed with both surface molecules (Figs. 1, 4). However, in some in- stances, shedding of the surface coat was not complete and varying amounts of label were internalised and re- mained on membrane associated with or adjacent to the parasite surface "
  • Microscopy type: EM
  • Microscopy method: Monoclonal antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: surface during extracellular tachyzoite, some parasite plasma membrane during intracellular tachyzoite and after tachyzoite invasion, vesicles budding off zoite posterior during after tachyzoite invasion