PF3D7_0721600

PF3D7_0721600 (40S ribosomal protein S5) is a structural component of the small (40S) subunit of the Plasmodium falciparum 80S ribosome, resolved as a constituent of the native ribosome in multiple high-resolution cryo-EM structures spanning blood-stage schizonts and, most recently, in situ within infected erythrocytes (PMID:24913268, PMID:26432834, PMID:40825879). Its placement in the small subunit is consistent across structures determined in the context of antimalarial translation inhibitors that act on the ribosome, including emetine bound at the small-subunit E-site and mefloquine bound at the large-subunit GTPase-associated centre (PMID:24913268, PMID:28288098). Beyond its confirmed membership in the 40S subunit and its dynamic association with that complex across the intraerythrocytic developmental cycle (PMID:41315737), no experiment in the available corpus assigns S5 an individual molecular function, interaction, or phenotype distinct from the ribosomal complex.

1. 2014 Medium

   Establishing whether the P. falciparum ribosome could be resolved at near-atomic detail mattered for antimalarial target definition; the first cryo-EM structure placed S5 as a structural constituent of the small subunit.

   Evidence Cryo-EM at 3.2 Å of native Pf80S ribosome in complex with emetine

   PMID:24913268

   Open questions at the time

   • No S5-specific functional experiment performed
   • No S5 interaction or substrate assigned beyond ribosome membership
   • Emetine binding is a small-subunit E-site property, not attributed to S5
2. 2015 Medium

   To distinguish the parasite ribosome from the mammalian host, multiple reconstructions from blood-stage schizonts confirmed S5 as a small-subunit component within atomically modeled ribosomes.

   Evidence Cryo-EM reconstructions of native ribosomes from blood-stage schizonts with flexible-fitting atomic modeling

   PMID:26432834

   Open questions at the time

   • S5 confirmed structurally but no individual role tested
   • Species-differentiating features not attributed specifically to S5
3. 2017 Medium

   Resolving another antimalarial's binding site further validated the Pf80S model and again positioned S5 as a structural constituent of the small subunit.

   Evidence Cryo-EM at 3.2 Å with (+)-mefloquine bound; site-directed mutagenesis and parasite resistance assay

   PMID:28288098

   Open questions at the time

   • Mefloquine site is on the large subunit, not linked to S5
   • No S5-specific mutagenesis or functional assay
4. 2025 Medium

   Whether S5's ribosomal placement holds during active translation in the native cell was addressed by in situ cryo-ET, confirming S5 in the 40S subunit within infected erythrocytes and capturing drug-induced shifts in translating states.

   Evidence In situ cryo-electron tomography of translating ribosomes inside P. falciparum-infected human erythrocytes

   PMID:40825879

   Open questions at the time

   • S5-specific contribution to translation dynamics not isolated
   • Drug effect measured at the ribosome level, not attributed to S5
5. 2025 Low

   Whether S5's association with the 40S complex varies across the parasite life cycle was probed by thermal proteome profiling, which predicted S5 within the 40S complex with dynamic compositional changes across blood stages.

   Evidence Meltome-assisted profiling of protein complexes (MAP-X) across seven IDC timepoints in intact cells

   PMID:41315737

   Open questions at the time

   • Proteome-wide prediction, not an S5-specific validated experiment
   • Functional consequence of dynamic complex composition unknown
   • No reciprocal or orthogonal confirmation for S5 individually

• No experiment has yet assigned S5 an individual molecular function, direct interaction partner, or loss-of-function phenotype distinct from its role as a subunit of the 40S ribosome.
• No S5-specific knockdown/knockout or rescue reported
• No direct interaction mapping for S5 beyond bulk ribosome
• No S5-targeted mechanistic role in translation defined