PF3D7_1223400

PF3D7_1223400 (ATP2) is a putative P4-type phospholipid-transporting ATPase of P. falciparum that operates as part of a CDC50C–ATP2 complex during asexual blood-stage development (PMID:35862778). Gene tagging and conditional disruption place ATP2 in a physical complex with the CDC50C chaperone in trophozoites (PMID:35862778), and disruption of CDC50C, the obligate chaperone of ATP2, impairs endocytosis of host-cell hemoglobin and consequent hemozoin formation, and is essential for trophozoite maturation (PMID:35862778). Beyond its participation in the CDC50C–ATP2 complex and this maturation/endocytosis phenotype, the corpus establishes no direct biochemical characterization of ATP2 itself — its catalytic activity, lipid substrate specificity, and subcellular localization have not been dissected in the available evidence.

1. 2022 Medium

   It was unknown whether the putative P4-ATPase ATP2 acts alone or with a partner; identifying a stable CDC50C–ATP2 complex established the molecular context in which ATP2 functions in blood stages.

   Evidence Gene tagging and conditional gene disruption in P. falciparum asexual blood stages

   PMID:35862778

   Open questions at the time

   • No reciprocal Co-IP or in vitro reconstitution confirming the direct ATP2–CDC50C interaction
   • Stoichiometry and subcellular localization of the complex not defined
   • ATP2's own catalytic/flippase activity not measured
2. 2022 Medium

   It was unclear what cellular process the ATP2 complex serves; conditional disruption of its chaperone CDC50C tied the complex to hemoglobin endocytosis, hemozoin formation, and trophozoite maturation.

   Evidence Conditional gene disruption of CDC50C with endocytosis, hemozoin, and maturation readouts in P. falciparum

   PMID:35862778

   Open questions at the time

   • Phenotype was scored via CDC50C disruption; direct functional dissection of ATP2 alone not reported
   • Mechanistic link between putative lipid flipping and endocytosis not established
   • Whether ATP2 loss phenocopies CDC50C loss not shown

• The enzymatic activity, lipid substrate, membrane localization, and direct (ATP2-specific) contribution to endocytosis remain uncharacterized.
• No in vitro or in vivo demonstration of ATP2 phospholipid-flippase activity
• No lipid substrate specificity determined
• No direct conditional disruption of ATP2 itself with phenotype