PEX3

PEX3 is predicted to be a peroxin of the peroxisome biogenesis machinery in Toxoplasma gondii, identified as part of a complete set of peroxins recovered by bioinformatic screening of apicomplexan genomes, consistent with the presence of peroxisome biogenesis, division, and protein import machinery in Coccidia (PMID:29126146). No direct experimental characterization of the T. gondii PEX3 protein itself has been reported in the available corpus. In a distinct host-directed context, host cell PEX3 physically interacts with the T. gondii dense granule protein GRA23, as shown by pull-down/mass spectrometry, bimolecular fluorescence complementation, and co-immunoprecipitation, indicating the parasite may engage host peroxisomal factors during infection (PMID:40417354). The functional consequences of this interaction and any activity of the parasite's own PEX3 remain uncharacterized in the available corpus.

1. 2017 Low

   Whether T. gondii possesses the genetic capacity for peroxisome biogenesis was unknown; genomic screening established that a complete peroxin set, including PEX3, is present, placing PEX3 within a candidate peroxisome biogenesis pathway.

   Evidence Bioinformatic/genomic screening for peroxins and PTS1/PTS2 targeting signals across apicomplexan genomes

   PMID:29126146

   Open questions at the time

   • Computational prediction only; no experimental validation of T. gondii PEX3 protein function or localization
   • Whether peroxisomes are actually assembled at any life cycle stage is not demonstrated
   • No demonstrated role for PEX3 in parasite biology
2. 2025 Medium

   Whether the parasite engages host peroxisomal machinery was unaddressed; identification of a physical interaction between host PEX3 and the parasite dense granule protein GRA23 established a candidate parasite-host interface at the peroxisome.

   Evidence Pull-down/mass spectrometry, BiFC, and Co-IP in a single study

   PMID:40417354

   Open questions at the time

   • No functional consequence of the PEX3-GRA23 interaction demonstrated
   • Interaction is with host PEX3, not the parasite's own PEX3 ortholog
   • Whether host peroxisomal function is modulated during infection is untested

• The biochemical activity, localization, and in vivo role of the T. gondii PEX3 protein itself remain unknown, as does the functional outcome of the host PEX3-GRA23 interaction.
• No knockout, knockdown, or rescue of T. gondii PEX3
• No demonstration of peroxisome assembly or PEX3 localization in the parasite
• No functional readout linking the host PEX3-GRA23 interaction to infection outcome