PF3D7_0930800

PF3D7_0930800 (PfRCC-PIP) is an essential Plasmodium falciparum protein that functions as a scaffold coordinating phosphorylation and dephosphorylation, established through direct interaction and functional assays (PMID:30429842). It directly binds P. falciparum Protein Phosphatase type-1 (PfPP1) in vitro and forms a complex with PfPP1 in parasite lysate, acting as a major regulatory partner of the phosphatase (PMID:30429842); in a heterologous Xenopus oocyte system, PfRCC-PIP interacts with endogenous PP1 and synergizes with suboptimal progesterone to drive oocyte maturation, indicating that it activates PP1 activity (PMID:30429842). Its RCC1 motif-containing region additionally binds the parasite kinase CDPK7, marking the protein as a kinase-anchoring platform as well as a phosphatase anchor (PMID:30429842). Attempted knockout failed to yield viable parasites, indicating the gene is essential for P. falciparum survival (PMID:30429842). Beyond these interaction and essentiality findings, no further mechanistic detail — including substrate specificity, structural basis of binding, or the functional consequence of the CDPK7 association — has been characterized in the available corpus.

1. 2018 Medium

   It was unknown which regulatory proteins govern PfPP1 in P. falciparum; identifying a direct PfPP1-binding partner established PF3D7_0930800 as a phosphatase-anchoring regulator.

   Evidence In vitro direct interaction assay plus co-immunoprecipitation/complex detection in parasite lysate

   PMID:30429842

   Open questions at the time

   • The PfPP1-binding motif/interface on PF3D7_0930800 was not mapped by mutagenesis
   • Substrates dephosphorylated by the PfPP1 complex were not identified
2. 2018 Medium

   Whether the interaction was merely physical or functionally regulatory was open; a heterologous oocyte assay showed PfRCC-PIP activates PP1 activity.

   Evidence Xenopus oocyte maturation assay with progesterone dose-response and endogenous PP1

   PMID:30429842

   Open questions at the time

   • The activating effect was shown on endogenous Xenopus PP1, not directly quantified on PfPP1 in the parasite
   • Physiological process in the parasite regulated by this activation is undefined
3. 2018 Low

   It was unclear whether the protein engaged only phosphatases; binding of its RCC1 motif region to CDPK7 established it as a dual kinase/phosphatase anchor.

   Evidence Region-specific protein interaction assay with CDPK7

   PMID:30429842

   Open questions at the time

   • Single interaction assay without mutagenesis validation or defined functional consequence
   • No reciprocal or in-parasite confirmation of the CDPK7 association
   • Whether kinase and phosphatase binding are simultaneous or mutually exclusive is unknown
4. 2018 Medium

   The biological importance of the gene was unknown; failure to obtain viable knockouts indicated essentiality for blood-stage survival.

   Evidence Reverse genetics / attempted gene knockout

   PMID:30429842

   Open questions at the time

   • Essentiality inferred from KO failure, not confirmed by conditional knockdown/knockout
   • The essential stage and process were not defined

• How PF3D7_0930800 integrates PfPP1 and CDPK7 activities on shared substrates, and which cellular process depends on this scaffold, remains unresolved.
• No substrates of the coordinated kinase/phosphatase platform identified
• No structural model of the scaffold or its binding interfaces
• Subcellular localization and stage-specific role uncharacterized