PF3D7_0933200

PF3D7_0933200 (calcyclin-binding protein) is a subunit of the functional Plasmodium falciparum SCF E3 ubiquitin ligase complex, in which it associates with PfCullin-1, PfRbx1, PfSkp1, and PfFBXO1; this assembled complex has demonstrable in vitro ubiquitination activity (PMID:38416790). Its specific biochemical contribution to the complex has not been dissected in the available corpus, and beyond complex membership no substrate or catalytic role is assigned to this subunit (PMID:38416790). In the rodent parasite P. yoelii nigeriensis, the ortholog (PyCacyBP) is expressed as a ~27 kDa protein across all blood stages and exists in both monomeric and dimeric forms (PMID:36707015).

1. 2023 Low

   Whether the calcyclin-binding protein ortholog is expressed during parasite blood stages and what physical form it adopts was previously undefined; characterizing this established its stage expression and oligomeric behavior.

   Evidence Molecular cloning, recombinant expression, and Western blot of P. yoelii nigeriensis parasite lysate with biophysical characterization

   PMID:36707015

   Open questions at the time

   • Establishes expression and monomer/dimer state but assigns no functional mechanism
   • Does not connect the ortholog to any complex or enzymatic activity
   • Findings are in P. yoelii nigeriensis, not directly in P. falciparum
2. 2024 Medium

   Whether calcyclin-binding protein participates in a defined P. falciparum ubiquitination machinery was unknown; showing it co-purifies with an SCF complex that is enzymatically active established it as a bona fide subunit of a functional E3 ubiquitin ligase.

   Evidence Immunoprecipitation, in vitro protein-protein interaction assays, and in vitro ubiquitination assay in P. falciparum

   PMID:38416790

   Open questions at the time

   • The specific functional contribution of calcyclin-binding protein within the complex is not dissected
   • No substrate of the complex attributable to this subunit is identified
   • Reciprocal Co-IP and activity assay are from a single lab

• The precise biochemical role of PF3D7_0933200 within the PfSCF complex — including whether it contributes to substrate recognition, complex assembly, or regulation — remains unresolved.
• No substrate or adaptor function assigned to this subunit specifically
• No structural model of the subunit within the complex
• Functional consequence of its monomer/dimer state is unknown