BTP2

BTP2 (PF3D7_0704100) is a transmembrane component of the Plasmodium falciparum basal complex that is specifically required for the separation of individual daughter merozoites during asexual schizogony (PMID:41706859). During schizont development BTP2 localizes to the basal complex, concentrating at the leading edge of the emerging inner membrane complex (PMID:35972967). Genetic ablation of BTP2 yields daughter cells that remain enveloped by membranes but fail to individualize, producing multiorganellar mutants; notably, the contractile function of the basal complex ring stays intact in BTP2-null parasites, isolating BTP2's role to daughter cell separation rather than to constriction itself (PMID:41706859). BTP2's contribution is stage-restricted: it is not detected during gametocytogenesis, in contrast to other basal complex proteins, indicating it is not deployed during transmission-stage development (PMID:35972967). Beyond its transmembrane basal complex localization and its role in merozoite individualization, no further biochemical mechanism—such as how BTP2 is recruited or what it binds within the complex—has been characterized in the available corpus.

1. 2019 Low

   The first question was whether BTP2 is a genuine basal complex resident, addressed by placing it within the known contractile machinery of the complex.

   Evidence Immunofluorescence localization and reported interaction/co-localization with PfCINCH and PfBCP1 during schizogony

   PMID:31824870

   Open questions at the time

   • Interaction reported only as a citation summary with no primary experimental detail in this corpus entry
   • No reciprocal validation or direct binding assay for the PfCINCH/PfBCP1 association
   • Functional role of BTP2 not addressed
2. 2022 Medium

   Establishing where and when BTP2 acts, endogenous tagging showed it localizes to the leading edge of the emerging inner membrane complex in schizonts but is absent from the gametocyte basal complex equivalent, defining its role as stage-restricted to asexual replication.

   Evidence Immunofluorescence of PfBTP2-3xHA endogenously tagged parasites compared across asexual and gametocyte stages

   PMID:35972967

   Open questions at the time

   • Does not define BTP2's molecular function at the basal complex
   • Recruitment mechanism to the leading edge unknown
   • Single lab and single strain
3. 2026 High

   The functional question—what BTP2 actually does—was resolved by knockout, showing it is specifically required for individual daughter cell separation, a step distinct from basal complex contraction.

   Evidence Conditional/genetic knockout with expansion microscopy and DNA-PAINT imaging; phenotypic characterization of BTP2-null parasites

   PMID:41706859

   Open questions at the time

   • Molecular mechanism by which BTP2 drives individualization is undefined
   • How the transmembrane topology relates to its separation function is unresolved
   • Direct binding partners within the basal complex not biochemically mapped

• It remains unknown how BTP2 mechanistically mediates daughter cell separation and what molecular interactions or membrane activities underlie its transmembrane function at the basal complex leading edge.
• No defined biochemical activity or direct interactor set for BTP2
• No structural model of BTP2 within the basal complex
• Recruitment pathway to the inner membrane complex leading edge uncharacterized