PF3D7_1408600

PF3D7_1408600 (S8e) is a constituent protein of the small (40S) subunit of the Plasmodium falciparum 80S ribosome, established solely through structural biology (PMID:24913268, PMID:40825879). High-resolution cryo-EM of the Pf80S ribosome placed S8e within the small subunit architecture (PMID:24913268), subsequent cryo-EM reconstructions of blood-stage schizont ribosomes confirmed its presence and helped delineate structural differences from mammalian ribosomes (PMID:26432834), and in situ cryo-electron tomography of actively translating ribosomes inside infected erythrocytes established S8e as a small-subunit component in the physiological translation context during elongation (PMID:40825879). Beyond this membership in the 40S subunit, no specific enzymatic activity, binding partner, post-translational modification, or individual functional role has been experimentally attributed to S8e in the available corpus.

1. 2014 Medium

   Before any structure of the malarial ribosome, the composition and molecular architecture of the P. falciparum small subunit were undefined; the first high-resolution cryo-EM structure resolved the subunit and placed S8e within it, establishing S8e as a bona fide small-subunit component.

   Evidence Cryo-EM structure of the P. falciparum 80S ribosome at 3.2 Å in complex with emetine

   PMID:24913268

   Open questions at the time

   • No functional experiment interrogates S8e itself; only its presence in the complex is inferred from the structure
   • No binding partner, PTM, or enzymatic role assigned to S8e specifically
2. 2015 Low

   To test whether the ribosome architecture holds in natively purified particles and how it diverges from the host, cryo-EM reconstructions from blood-stage schizonts confirmed S8e as a small-subunit component and identified structural differences from mammalian ribosomes.

   Evidence Five sub-nanometer cryo-EM reconstructions with atomic model building by flexible fitting from P. falciparum schizont ribosomes

   PMID:26432834

   Open questions at the time

   • Establishes composition only; no experiment interrogates S8e function or interactions
   • Does not localize S8e-specific structural divergences from the host protein
3. 2025 Medium

   To determine whether S8e is part of the ribosome under physiological translation rather than only in purified particles, in situ cryo-ET of actively translating ribosomes inside infected erythrocytes confirmed S8e in the small subunit across elongation states.

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

   PMID:40825879

   Open questions at the time

   • No experiment isolates the contribution of S8e to elongation
   • No functional or interaction data specific to S8e

• It remains unknown whether S8e has any function, interaction, or regulatory role beyond its structural membership in the 40S subunit, and whether it is dispensable or essential in P. falciparum.
• No genetic knockout/knockdown data for S8e
• No binding partners or PTMs identified
• No S8e-specific role in translation initiation, elongation, or subunit assembly established