VPS9

PF3D7_0815800 (VPS9) is a putative vacuolar protein sorting-associated protein implicated in endosomal/vesicular trafficking in Plasmodium, known in the available corpus only through its physical associations rather than direct functional assays. In P. falciparum asexual stages, VPS9 co-immunoprecipitates with PfVps16, placing it as an associated component of the PfVps-C/CORVET tethering complex that also contains Vps11, Vps16, Vps18, Vps33 and the CORVET subunit PfVps3 (PMID:40626728), and its peptides are enriched in the clathrin heavy chain interactome of trophozoites, consistent with an association with clathrin-coated vesicle machinery (PMID:32098816). In P. berghei, a VPS9 homolog is phosphorylated at S767 in a PKG-regulated manner in gliding ookinetes (PMID:24594931). Beyond these association and phosphosite observations, no direct functional experiments on PF3D7_0815800 itself have been reported in the available corpus, and its proposed Rab5 GEF activity has not been experimentally demonstrated.

1. 2014 Low

   The first question was whether VPS9 participates in a regulated signaling pathway in the parasite; phosphoproteomics revealed a P. berghei VPS9 homolog is phosphorylated in a PKG-dependent context during ookinete gliding, linking it to a regulated trafficking process.

   Evidence Quantitative phosphoproteomics of P. berghei ookinetes with PKG perturbation, detecting phosphorylation at S767

   PMID:24594931

   Open questions at the time

   • Single phosphoproteomic dataset with no functional follow-up on VPS9 specifically; the authors note the phosphosite is likely not directly phosphorylated by PKG
   • The proposed Rab5 GEF activity is inferred, not demonstrated
   • Finding is in P. berghei, not directly in PF3D7_0815800
2. 2020 Low

   To ask which trafficking machinery VPS9 associates with, a clathrin interactome was profiled, and VPS9 peptides were enriched, implicating it in clathrin-coated vesicle-associated transport.

   Evidence Clathrin nanobody pulldown followed by mass spectrometry in P. falciparum trophozoites

   PMID:32098816

   Open questions at the time

   • Single pulldown/MS experiment without orthogonal validation of the VPS9 enrichment
   • Does not establish direct binding versus co-enrichment as part of a larger assembly
   • No functional consequence of the clathrin association tested
3. 2025 Low

   To define VPS9's complex membership, PfVps16 was immunoprecipitated, and VPS9 co-purified with the canonical Vps-C/CORVET subunits, positioning it as an associated component of a tethering complex in asexual parasites.

   Evidence Co-immunoprecipitation and mass spectrometry of PfVps16 in P. falciparum asexual stages

   PMID:40626728

   Open questions at the time

   • Single Co-IP/MS from one lab with no orthogonal or reciprocal validation of the VPS9 interaction specifically
   • Does not establish whether VPS9 is a stoichiometric subunit or a transient associate
   • No functional role of VPS9 within the complex demonstrated

• Whether PF3D7_0815800 functions as a Rab5 GEF, and its direct role in endosomal trafficking or apical organelle biogenesis, remains untested by any direct functional or biochemical experiment.
• No genetic knockout, knockdown, or conditional depletion of PF3D7_0815800 reported
• No biochemical demonstration of guanine nucleotide exchange activity toward Rab5
• No localization or trafficking-phenotype data specific to VPS9