ICAP18

ICAP18 is an apicomplexan-specific subunit of the Toxoplasma gondii mitochondrial ATP synthase complex, lacking homologs outside the Apicomplexa (PMID:30204085). Structural modeling places it as a distant relative of mammalian stator subunits, and biochemical complex analysis confirmed that it co-purifies as an integral part of the assembled ATP synthase (PMID:30204085). Beyond its identification and confirmed complex membership (PMID:30204085), no direct functional depletion of ICAP18 itself has been characterized in the available corpus.

1. 2018 Medium

   Whether the Toxoplasma ATP synthase contains lineage-specific subunits beyond the canonical conserved core was unknown; identifying ICAP18 as a genuine complex member established that the parasite ATP synthase is built partly from apicomplexan-specific components.

   Evidence Sequence-based identification, structural modeling, and biochemical complex membership assay in Toxoplasma gondii

   PMID:30204085

   Open questions at the time

   • Direct functional depletion of ICAP18 itself was not performed (only ICAP2 depletion was characterized)
   • The predicted stator function is inferred from structural modeling, not from a functional assay
   • The precise position and interaction partners within the complex are not resolved
2. 2026 Low

   A review contextualized ICAP18 as a stator-related ATP synthase subunit linked to crista formation and maintenance, integrating it into the broader model of inner mitochondrial membrane organization.

   Evidence Review synthesis of prior experimental findings, no new experiments on ICAP18

   PMID:41789725

   Open questions at the time

   • No new direct experiment on ICAP18; the crista role is inferred from complex membership rather than tested for ICAP18 specifically
   • Causal contribution of ICAP18 to crista morphology not demonstrated

• The functional consequence of ICAP18 loss and its specific mechanistic contribution to stator function and ATP synthase activity remain unresolved.
• No conditional knockdown or knockout of ICAP18 reported
• No structural determination confirming the modeled stator position
• No measurement of ATP synthase activity or crista morphology upon ICAP18 depletion