PF3D7_0306900

PF3D7_0306900 (S23) is a structural component of the small (40S) subunit of the Plasmodium falciparum 80S ribosome, identified within the atomic organization of the small subunit by high-resolution cryo-EM of the native parasite ribosome (PMID:24913268, PMID:26432834). In situ cryo-electron tomography of P. falciparum-infected erythrocytes has placed the 40S subunit, including S23, within the molecular context of actively translating ribosomes across the elongation cycle in the native cellular environment (PMID:40825879). Beyond its membership in the 40S small ribosomal subunit as resolved by these structural studies, no specific biochemical activity, individual binding partner, or distinct functional role has been experimentally assigned to S23 itself in the available corpus.

1. 2014 Medium

   The first atomic-resolution view of the P. falciparum ribosome was needed to define the composition and organization of the parasite translation machinery, within which S23 could be placed as a small-subunit constituent.

   Evidence Cryo-EM structure at 3.2 Å of the native P. falciparum 80S ribosome bound to emetine, resolving the 40S subunit

   PMID:24913268

   Open questions at the time

   • S23 is present as a 40S component but is not individually characterized or functionally validated
   • no S23-specific interaction or activity distinguished from the bulk subunit
   • the emetine E-site drug interaction is a small-subunit property, not an S23-specific one
2. 2015 Medium

   Whether the parasite small subunit carries structural or dynamic features distinguishing it from the mammalian ribosome — a question relevant to selective targeting — was addressed by resolving multiple conformational states.

   Evidence Five cryo-EM reconstructions of the schizont-stage 80S ribosome with flexible atomic model building, confirming S23 in the small subunit

   PMID:26432834

   Open questions at the time

   • S23 is a constituent of the resolved subunit but is not individually functionally interrogated
   • no assignment of an S23-specific role in the observed conformational dynamics
3. 2025 Medium

   To move from purified structures to the native functional context, the ribosome was resolved inside intact infected cells across translating states, establishing where the 40S subunit and S23 sit within the elongation cycle in situ.

   Evidence In situ cryo-electron tomography of P. falciparum-infected human erythrocytes yielding eight high-resolution structures of translating ribosomes

   PMID:40825879

   Open questions at the time

   • S23 is resolved as a structural component but is not individually dissected
   • no mechanistic role for S23 in elongation established beyond subunit membership

• It remains unknown whether S23 has any function, interaction, or property distinct from its structural membership in the 40S subunit.
• no genetic knockdown/knockout or essentiality data for S23 specifically
• no S23-specific binding partner, RNA contact, or biochemical activity defined
• no evidence for extraribosomal or moonlighting roles