PIC4

PIC4 (PF3D7_0308300) is a component of the PhIL1-associated inner membrane complex (IMC) of Plasmodium falciparum (PMID:33830607). It was first identified as a PhIL1-interacting candidate through immunoprecipitation/mass spectrometry of the gametocyte IMC (PMID:28985225), and its association with the PhIL1-defined compartment was corroborated in asexual blood-stage parasites by BioID proximity proteomics using PhIL1 as bait, with endogenous GFP-tagging confirming IMC localization (PMID:33830607). Beyond this membership in the PhIL1-associated IMC and its subcellular localization, no direct functional characterization of PIC4 itself has been reported in the available corpus.

1. 2017 Low

   To define the protein composition of the PhIL1-associated IMC, an interactome was needed; this placed PIC4 among the candidate members of that complex.

   Evidence Immunoprecipitation followed by mass spectrometry of the gametocyte IMC in P. falciparum

   PMID:28985225

   Open questions at the time

   • Single Co-IP/MS experiment with no independent validation of PIC4 specifically
   • Does not distinguish direct binding to PhIL1 from indirect complex membership
   • No functional role for PIC4 tested
2. 2021 Medium

   To confirm that the candidate was a genuine IMC constituent rather than a co-purification artifact, orthogonal proximity labelling and direct localization were required; this established PIC4 as an IMC-localized PhIL1-proximal protein in asexual stages.

   Evidence BioID proximity-dependent biotinylation proteomics with PhIL1 as bait plus endogenous GFP-tagging for localization in P. falciparum asexual blood-stage parasites

   PMID:33830607

   Open questions at the time

   • No functional perturbation of PIC4 (knockout, knockdown, or conditional depletion) reported
   • Molecular activity and binding partners of PIC4 itself undefined
   • Both proteomic identifications originate from a related experimental lineage centered on PhIL1

• The molecular function of PIC4, its specific role within the IMC, and the consequences of its loss for parasite biology remain unestablished in the available corpus.
• No loss-of-function phenotype for PIC4 determined
• No structural or biochemical activity assigned to PIC4
• Whether PIC4 binds PhIL1 directly or via other complex members is unknown