| Annotation aspect | Evidence summary | Key source(s) with publication year and URL |
|---|---|---|
| Identity | The requested target is UniProt A0A1D1VEY6 from *Ramazzottius varieornatus*, annotated as a Cu/Zn superoxide dismutase family protein. Direct literature linking the exact locus tag **RvY_09480-1** to a named experimental protein is limited; available *R. varieornatus* studies instead describe multiple Cu/Zn SOD paralogs such as RvSOD15, so functional annotation for A0A1D1VEY6 should be treated as family-based unless sequence-level mapping is independently confirmed (pqac-00000000, pqac-00000005). | Sim & Inoue 2023, *Acta Crystallographica F*, https://doi.org/10.1107/S2053230X2300523X |
| Enzyme class/reaction | UniProt assigns EC 1.15.1.1, the canonical superoxide dismutase reaction converting superoxide radicals to hydrogen peroxide and oxygen. In tardigrades, Cu/Zn SODs are discussed as core antioxidant enzymes implicated in oxidative-stress control during desiccation, UV exposure, and rehydration-associated stress (pqac-00000006, pqac-00000015). | Sadowska-Bartosz & Bartosz 2024, *IJMS*, https://doi.org/10.3390/ijms25158393; Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X |
| Cofactors & key residues | Cu/Zn SOD family members require copper and zinc; crystallography on a *R. varieornatus* paralog confirmed bound Cu and Zn. However, some tardigrade paralogs carry substitutions in catalytic/metal-binding residues; notably RvSOD15 has Val87 replacing a histidine normally involved in copper coordination, raising concern that some paralogs may not retain canonical SOD activity (pqac-00000001, pqac-00000005, pqac-00000018). | Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X; Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |
| Structure/domains | The UniProt/domain assignment places A0A1D1VEY6 in the Cu/Zn SOD family with SOD_Cu/Zn domains. A structurally characterized *R. varieornatus* paralog (RvSOD15) adopts the expected Cu/Zn SOD fold: a Greek-key β-barrel with electrostatic and metal-binding loops, supporting domain-based inference that A0A1D1VEY6 is a Cu/Zn SOD-like protein unless proven otherwise (pqac-00000005). | Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X |
| Subcellular localization | Tardigrade SOD complements are predicted to localize to mitochondria, cytosol, and peroxisomes at the family level. For one *R. varieornatus* Cu/Zn SOD paralog, an N-terminal signal peptide was predicted, suggesting secretion; therefore localization may vary among paralogs, and the exact localization of A0A1D1VEY6 remains inferential without direct experiment (pqac-00000000, pqac-00000017). | Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X; Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |
| Biological role in tardigrades | Antioxidant proteins including SODs are repeatedly implicated in tardigrade resistance to desiccation-, UV-, and rehydration-associated oxidative damage. Comparative genomics concludes that oxidant-protection proteins such as SODs and peroxiredoxins were extensively duplicated in tardigrades, consistent with a protective role in anhydrobiosis and broader extremotolerance (pqac-00000006, pqac-00000016). | Yoshida et al. 2017, *PLOS Biology*, https://doi.org/10.1371/journal.pbio.2002266; Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X |
| Gene family expansion | *R. varieornatus* shows a pronounced SOD expansion versus typical metazoans. A 2024 review reports 16 SODs in running text but a table value of **17 SOD genes** for *R. varieornatus* (vs **3 in humans**), so the safest summary is a large lineage-specific expansion with a minor reporting inconsistency between text and table (pqac-00000004, pqac-00000017, pqac-00000019). | Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |
| Notable unusual features in *R. varieornatus* SODs | Several *R. varieornatus* SOD paralogs are structurally atypical: deletions of the electrostatic loop or β3 sheet, truncations, and substitutions in copper-binding residues were reported. The authors specifically suggest that RvSOD15 and some other paralogs may have evolved to lose canonical SOD function, meaning family expansion does not equal expansion of active enzymes (pqac-00000003, pqac-00000005, pqac-00000006, pqac-00000018). | Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X; Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |
| Quantitative data/statistics | Reported statistics relevant to tardigrade oxidative-stress biology include **17 SOD genes** in *R. varieornatus* (table value), and far fewer desiccation-induced transcriptional changes in *R. varieornatus* than in *H. dujardini* (**64 genes, 0.5%** under fast drying; **307 genes, 2.2%** under slow drying). In a copper-tolerance assay on another tardigrade species, **R. oberhaeuseri** showed a **24 h EC50 of 310 µg/L** Cu (95% CI 295–328), illustrating that tardigrades pair antioxidant capacity with strong toxicant tolerance, though this is not a direct measurement for A0A1D1VEY6 (pqac-00000010, pqac-00000016, pqac-00000019). | Hygum et al. 2017, *Frontiers in Physiology*, https://doi.org/10.3389/fphys.2017.00095; Yoshida et al. 2017, https://doi.org/10.1371/journal.pbio.2002266; Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |
| Applications | The most defensible application is annotation and prioritization: Cu/Zn SOD-like genes in *R. varieornatus* are candidates for stress-tolerance engineering and mechanistic studies of anhydrobiosis, but the 2023 structural work cautions that some paralogs may be neofunctionalized or inactive. Thus A0A1D1VEY6 is relevant to comparative genomics, protein engineering, and extremotolerance research, yet it should not be assumed to be an active canonical SOD without direct biochemical validation (pqac-00000006, pqac-00000018). | Sim & Inoue 2023, https://doi.org/10.1107/S2053230X2300523X; Sadowska-Bartosz & Bartosz 2024, https://doi.org/10.3390/ijms25158393 |


*Table: This table summarizes the strongest evidence-based functional annotation points for the *Ramazzottius varieornatus* Cu/Zn SOD target A0A1D1VEY6. It highlights where evidence is direct versus family-level inference, which is especially important because several tardigrade SOD paralogs appear structurally unusual or potentially noncanonical.*