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

version 3 (curated until May 28, 2011)

A Toxoplasma gondii leucine-rich repeat protein binds phosphatase type 1 protein and negatively regulates its activity.

Daher, W., Oria, G., Fauquenoy, S., Cailliau, K., Browaeys, E., Tomavo, S., Khalife, J. (2007 Sep, Eukaryot Cell)

We have characterized the Toxoplasma gondii protein phosphatase type 1 (TgPP1) and a potential regulatory binding protein belonging to the leucine-rich repeat protein family, designated TgLRR1. TgLRR1 is capable of binding to TgPP1 to inhibit its activity and to override a G(2)/M cell cycle checkpoint in Xenopus oocytes. In the parasite, TgLRR1 mRNA and protein are both highly expressed in the rapidly replicating and virulent tachyzoites, while only low levels are detected in the slowly dividing and quiescent bradyzoites. TgPP1 mRNA and protein levels are equally abundant in tachyzoites and bradyzoites. Affinity pull down and immunoprecipitation experiments reveal that the TgLRR1-TgPP1 interaction takes place in the nuclear subcompartment of tachyzoites. These results are consistent with those of localization studies using both indirect immunofluorescence with specific polyclonal antibody and transient transfection of T. gondii vector expressing TgLRR1 and TgPP1. The inability to obtain stable transgenic tachyzoites suggested that overexpression of TgLRR1 and TgPP1 may impair the parasite's growth. Together with the activation of Xenopus oocyte meiosis reinitiation, these data indicate that TgLRR1 protein could play a role in the regulation of the T. gondii cell cycle through the modulation of phosphatase activity.

PubMed: 17660360, full text

Localisation information

TGME49_067550 (LRR1) hypothetical protein, conserved

Experimental localisation: nucleus during tachyzoite, cytoplasm during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In tachyzoites, TgLRR1 was clearly present in the nucleus (green fluorescence) of all parasites examined, colocalizing with the propidium iodine (red fluorescence) (Fig. 7A). The strong nuclear localization of TgLRR1 can be seen in the yellow merged color (Fig. 7A, right panel). However, a cytoplasmic staining was also observed."
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein, cMyc tag
  • Strain: 76K
  • Gene model mapping comments: Blast from DQ437870, annotation doesn't match but gene model agrees with RACE experiments in 17660360
  • Localisation record: nucleus and cytoplasm during tachyzoite

TGME49_110700 (PP1) serine/threonine protein phosphatase, putative

Experimental localisation: nucleus during tachyzoite, cytoplasm during tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "When the tachyzoites were examined for the expression of TgPP1, we observed a weak but specific staining in the nucleus (Fig. 7B). In addition, we observed that polyclonal anti-PP1 antibodies revealed a signal associated with an organelle of the parasite that colocalized with staining obtained with anti-ROP1 antibodies"
  • Microscopy type: Light
  • Microscopy method: polyclonal antibody directly to protein, cMyc tag
  • Strain: 76K
  • Gene model mapping comments: Blast from DQ437871, annotation doesn't match but gene model agrees with RACE experiments in 17660360
  • Localisation record: nucleus and cytoplasm during tachyzoite
  • Comment: On ToxoDB 4.3: Blast from DQ437871, annotation doesn't match and gene model is currently wrong – comment made