| Evidence scope | Gene/protein identity / aliases | Organism | Localization evidence | Enzymatic function / substrate evidence | Physiological role / phenotype | Key reference(s) with year and URL/DOI |
|---|---|---|---|---|---|---|
| Verified target identity | **Pmp20 / Pmp20p**; UniProt **O14313**; peroxisomal membrane associated protein 20; peroxiredoxin homolog; member of the **peroxiredoxin family / Prx5-like subgroup**. A comparative sequence analysis of fungal PMP20 proteins explicitly includes an **S. pombe PMP20 homologue** among AhpC/TSA-related proteins, supporting that the SCHPO target belongs to the same redoxin/peroxiredoxin family as yeast alkyl-hydroperoxide reductases (pqac-00000004, pqac-00000008). | *Schizosaccharomyces pombe* | In aging/quality-control reviews, **Pmp20p is treated as a peroxisomal antioxidant enzyme in S. pombe**, grouped with catalase and glutathione peroxidase in peroxisomes (pqac-00000001, pqac-00000007, pqac-00000012). | Family-level inference from AhpC/TSA/peroxiredoxin homology indicates thiol-dependent peroxide reduction chemistry (pqac-00000003, pqac-00000004, pqac-00000008). | Supports interpretation of SCHPO Pmp20 as a **peroxisomal redox-protective enzyme** rather than an unrelated PMP20 from another species (pqac-00000001, pqac-00000007). | Lee et al., 1999, *J Biol Chem*, https://doi.org/10.1074/jbc.274.8.4537; Manivannan et al., 2012, *Front Oncol*, https://doi.org/10.3389/fonc.2012.00050 |
| **S. pombe-specific** functional evidence | **Pmp20p** in fission yeast is discussed together with thioredoxin peroxidase and glutathione peroxidase as a peroxisomal oxidative-stress defense protein (pqac-00000001, pqac-00000007). | *S. pombe* | Review evidence places Pmp20p in the **peroxisome** of fission yeast (pqac-00000001, pqac-00000007, pqac-00000012). | In vitro data summarized in review literature indicate that **Pmp20p inhibited thermal aggregation of citrate synthase at 43°C**, alongside other peroxide-detoxifying enzymes; this supports a **secondary chaperone-like activity** in addition to antioxidant/peroxidase function (pqac-00000001, pqac-00000007). | Proposed role in **organelle quality control** and stress protection within peroxisomes; evidence is direct for chaperone-like anti-aggregation activity but limited for a detailed substrate profile in *S. pombe* itself (pqac-00000001, pqac-00000007). | Han et al., 2015, *Mycobiology*, https://doi.org/10.5941/MYCO.2015.43.3.272; Manivannan et al., 2012, https://doi.org/10.3389/fonc.2012.00050 |
| **S. pombe-specific** pathway/role inference | Pmp20p is part of the **peroxisomal ROS-scavenging module** imported by Pex5-dependent pathways in yeast aging models (pqac-00000012). | *S. pombe* | Peroxisomal compartment assignment is integrated into models where efficient import of catalase and **Pmp20p** minimizes oxidative damage to peroxisomal proteins and membrane lipids (pqac-00000012). | Substrate not specified directly for *S. pombe* in the accessible excerpts, but the enzyme is treated as a **ROS scavenger / peroxiredoxin** acting on peroxides inside peroxisomes (pqac-00000001, pqac-00000012). | Supports a role in **maintenance of peroxisomal integrity**, limiting oxidative injury and fitting into broader peroxisome quality-control and aging pathways (pqac-00000012, pqac-00000013). | Beach et al., 2012, *Front Physiol*, https://doi.org/10.3389/fphys.2012.00283; Manivannan et al., 2012, https://doi.org/10.3389/fonc.2012.00050 |
| Closely related yeast evidence for catalytic inference | **Ahp1p** is a yeast AhpC/TSA-family antioxidant closely related to fungal PMP20 proteins; sequence comparison places **S. pombe PMP20** among these homologs (pqac-00000004, pqac-00000008). | *Saccharomyces cerevisiae* (inference to SCHPO family member) | Ahp1p contains a peroxisomal-like sorting signal, though some related proteins can vary in distribution; the broader family includes fungal peroxisomal proteins (pqac-00000003, pqac-00000008). | Direct experiments show **Ahp1p is specific for organic peroxides (e.g., tert-butyl hydroperoxide) rather than H2O2**, and requires the **thioredoxin/thioredoxin reductase system**, not glutathione, for antioxidant function (pqac-00000003, pqac-00000004). | Deletion causes **t-BOOH hypersensitivity**; overexpression increases resistance to organic peroxide stress, establishing the family as **alkyl-hydroperoxide defense proteins** (pqac-00000004). | Lee et al., 1999, *J Biol Chem*, https://doi.org/10.1074/jbc.274.8.4537 |
| Closely related yeast evidence for peroxisomal targeting | Fungal **Pmp20 orthologs** are described as **PTS1 proteins** with conserved C-terminal peroxisomal targeting signals; image/text evidence highlights the conserved **-AKL-COOH** motif in Pmp20 orthologs (pqac-00000015, pqac-00000016). | Methylotrophic yeasts (*Candida boidinii*, *Hansenula/ Ogataea polymorpha*) | Direct evidence shows Pmp20 orthologs are **localized to peroxisomes** and imported as **Pex5-recognized PTS1 proteins** (pqac-00000015, pqac-00000016). | These orthologs are peroxiredoxins with peroxide-detoxifying activity; in *C. boidinii*, CbPmp20 shows **glutathione peroxidase activity** and reacts with **alkyl hydroperoxides and H2O2** (pqac-00000015). | Strongly supports the localization/function model for SCHPO Pmp20 as a **peroxisomal redoxin enzyme** rather than a structural membrane constituent (pqac-00000015, pqac-00000016). | Aksam et al., 2009, *FEMS Yeast Res*, https://doi.org/10.1111/j.1567-1364.2009.00534.x |
| Closely related yeast evidence for peroxisomal integrity phenotype | Loss of **Pmp20/peroxiredoxin** in methylotrophic yeasts causes severe oxidative defects and **protein leakage from peroxisomes** (pqac-00000014, pqac-00000015). | *Hansenula/ Ogataea polymorpha* | Because the protein is peroxisomal, its deletion specifically compromises **peroxisomal integrity** under ROS-generating growth conditions (pqac-00000014, pqac-00000015). | Associated with increased ROS and lipid peroxidation when peroxisomal oxidative metabolism is active (pqac-00000015). | Deletion causes **severe growth defects on methanol**, **peroxisomal protein leakage**, and **necrotic cell death**, showing that Pmp20-family peroxiredoxins can be essential for preserving organelle compartmentalization and viability (pqac-00000014, pqac-00000015). | Aksam et al., 2009, *FEMS Yeast Res*, https://doi.org/10.1111/j.1567-1364.2009.00534.x; summarized in Manivannan et al., 2012, https://doi.org/10.3389/fonc.2012.00050 |
| Closely related yeast evidence for broader biological interpretation | Reviews of peroxisome biology and yeast PCD cite **absence of Pmp20 causing peroxisomal protein leakage and necrotic cell death**, placing Pmp20 among key **peroxisomal antioxidant/quality-control factors** (pqac-00000013, pqac-00000014, pqac-00000015). | Yeasts, especially methylotrophs; applied as functional context for SCHPO | Peroxisomal antioxidant localization is central to interpretation (pqac-00000013, pqac-00000015). | Reinforces peroxide-detoxification role of Pmp20-family proteins in organelles with high ROS burden (pqac-00000015). | Supports expert interpretation that SCHPO Pmp20 most likely protects the **peroxisomal lumen/membrane from oxidative damage** and may secondarily contribute to **protein quality control** (pqac-00000007, pqac-00000013, pqac-00000015). | Farrugia & Balzan, 2012, *Front Oncol*, https://doi.org/10.3389/fonc.2012.00064; Manivannan et al., 2012, https://doi.org/10.3389/fonc.2012.00050; Aksam et al., 2009, https://doi.org/10.1111/j.1567-1364.2009.00534.x |


*Table: This table summarizes direct and inferred evidence for the identity, localization, biochemical function, and biological roles of Schizosaccharomyces pombe Pmp20 (UniProt O14313). It separates S. pombe-specific findings from orthology-based inferences drawn from closely related yeast Pmp20/Ahp1 proteins.*