RTL9 (SIRH10 / Retrotransposon Gag-like 9) — curation notes

RTL9 is a eutherian sushi-ichi/Ty3-gypsy-derived (Gag-like) domesticated gene.
Human review is by orthology to mouse functional studies (ISS); human–mouse
orthologs are strongly conserved across the functional Gag module.

Function

• Unlike the secreted traps RTL5/RTL6, RTL9 is intracellular and lysosomal,
  acting within microglial lysosomes on phagocytosed fungal cell-wall material
  PMID:37834332.
• Required, via its C-terminal retroviral Gag capsid-like region, for degradation
  of zymosan (a fungal PAMP)
  PMID:37834332.

Curation decisions

• Because RTL9 acts intracellularly on the fungal material (not as an
  extracellular trap), the cellular-response framing GO:0071226 cellular response
  to molecule of fungal origin is retained, unlike RTL5/RTL6.
• Defense response to fungus is NOT proposed: only zymosan (a PAMP), not live
  fungal infection, was tested.
• The standalone GO:0045087 innate immune response proposal was dropped.