PF3D7_0704400

PF3D7_0704400 (PfPX2) is a Plasmodium falciparum PX domain-containing protein implicated in phosphoinositide-dependent membrane trafficking during schizont development (PMID:41125830). Its PX domain harbors both canonical and non-canonical PIP-binding motifs and a positively charged pocket, and in vitro binds all phosphoinositide species with a preference for PI3P, PI5P, and PI(3,5)P2 (PMID:41125830). Consistent with a trafficking role, PfPX2 localizes to the Golgi apparatus and micronemes in developing schizonts (PMID:41125830). Beyond this biochemical and localization characterization, the functional role of PfPX2 has not been established in the available corpus; its lipid-binding specificity has not been validated by mutagenesis, and its physical partners remain undefined.

1. 2025 Medium

   Whether PF3D7_0704400 is a functional phosphoinositide-binding protein was unknown; demonstrating that its PX domain binds specific PIP species established it as a lipid-recognition module with defined binding preferences.

   Evidence In silico structural analysis of the PX domain combined with in vitro lipid binding assays, in P. falciparum PfPX2

   PMID:41125830

   Open questions at the time

   • No mutagenesis of the predicted binding pocket to confirm specificity
   • Binding shown in vitro only; in vivo lipid engagement not demonstrated
   • Single lab, single study
2. 2025 Medium

   The subcellular context of PfPX2 was undefined; immunofluorescence placing it at the Golgi and micronemes in schizonts localized its activity to secretory/trafficking compartments.

   Evidence Immunofluorescence assay in P. falciparum developing schizonts

   PMID:41125830

   Open questions at the time

   • Functional consequence of this localization not tested
   • Single method (IFA) without orthogonal validation
   • Dynamics across the intraerythrocytic cycle not resolved
3. 2025 Low

   Whether PfPX2 associates with trafficking machinery was unknown; proximity labelling nominated candidate interactors consistent with Golgi-to-microneme vesicular transport.

   Evidence Proximity labelling identifying PfSortilin, clathrin heavy chain, and PfDyn1 as candidates, in P. falciparum

   PMID:41125830

   Open questions at the time

   • Proximity labelling nominates candidates but does not confirm direct physical interaction; no reciprocal or biochemical validation
   • No functional demonstration that PfPX2 participates in the trafficking pathway
   • Single lab, single method

• The cellular function of PfPX2 in parasite biology, and whether its PIP binding and putative trafficking partners are required for microneme protein sorting or parasite viability, remains unresolved.
• No genetic knockout/knockdown phenotype reported
• No confirmed direct interaction partner
• Contribution to microneme biogenesis or invasion untested