| Aspect (function/localization/partner/phenotype/quant data) | Key finding | Experimental basis (assay) | Organism/system | Citation (author year journal) + URL | Context ID |
|---|---|---|---|---|---|
| function | **S. pombe-specific:** Atg2 is required for starvation-induced autophagy; atg2Δ lacked CFP-Atg8 processing, consistent with blocked autophagy flux. | CFP-Atg8 processing assay under nitrogen starvation | *Schizosaccharomyces pombe* | Sun et al. 2013, *PLoS Genetics* — https://doi.org/10.1371/journal.pgen.1003715 | (pqac-00000033) |
| phenotype | **S. pombe-specific:** atg2Δ cells showed Atg8 puncta that were more numerous than wild type and long-lived, indicating defective progression/maturation of autophagic structures. | Time-lapse fluorescence microscopy of Atg8 puncta | *Schizosaccharomyces pombe* | Sun et al. 2013, *PLoS Genetics* — https://doi.org/10.1371/journal.pgen.1003715 | (pqac-00000033) |
| partner/localization | **S. pombe-specific:** Atg2 is required for retrograde trafficking of Atg9 from the PAS; in starved atg2Δ cells, Atg9 puncta almost completely overlapped with Atg8 puncta, indicating PAS retention. | Fluorescent protein co-localization microscopy (Atg9 with Atg8) in mutants | *Schizosaccharomyces pombe* | Sun et al. 2013, *PLoS Genetics* — https://doi.org/10.1371/journal.pgen.1003715 | (pqac-00000034) |
| partner/localization | **S. pombe-specific:** Ctl1 became largely restricted to the PAS in starved atg2Δ cells, supporting an Atg2-dependent recycling step for Ctl1 as well as Atg9. | Fluorescent localization of YFP-Ctl1 with Atg8 in mutants | *Schizosaccharomyces pombe* | Sun et al. 2013, *PLoS Genetics* — https://doi.org/10.1371/journal.pgen.1003715 | (pqac-00000034) |
| partner | **S. pombe-specific:** Ctl1 physically interacts with Atg9; together with the atg2Δ localization phenotype, this places Atg2 in the Atg9/Ctl1 trafficking module at the PAS. | Co-immunoprecipitation plus localization genetics | *Schizosaccharomyces pombe* | Sun et al. 2013, *PLoS Genetics* — https://doi.org/10.1371/journal.pgen.1003715 | (pqac-00000034) |
| localization | **S. pombe-specific:** Atg2 localizes to a sub-region of enlarged Atg8-positive phagophores in ctl1Δ cells, consistent with phagophore rim/subdomain localization rather than uniform distribution. | Dual-color fluorescence microscopy (Atg2-tdT with Atg8 marker) | *Schizosaccharomyces pombe* | Wang et al. 2023, *Nature Communications* — https://doi.org/10.1038/s41467-023-40530-4 | (pqac-00000008, pqac-00000010) |
| localization | **S. pombe-specific:** APEX2 EM labeling placed Atg2 at the tips/rims of cup-shaped phagophores; unlike Atg5, labeling was not evenly distributed over the phagophore. | Correlative ultrastructure with APEX2 electron microscopy | *Schizosaccharomyces pombe* | Wang et al. 2023, *Nature Communications* — https://doi.org/10.1038/s41467-023-40530-4 | (pqac-00000008, pqac-00000010) |
| quant data | **S. pombe-specific:** In Wang et al., approximately **80%** of open phagophores showed rim labeling for Atg2 by APEX2 EM quantification. | Quantified APEX2 EM localization | *Schizosaccharomyces pombe* | Wang et al. 2023, *Nature Communications* — https://doi.org/10.1038/s41467-023-40530-4 | (pqac-00000010) |
| quant data | **S. pombe-specific:** Following nitrogen starvation, **>80%** of Atg8- or Atg2-marked phagophores contained Rop1, supporting early co-recruitment of a curvature factor with Atg2 at forming phagophores. | Live-cell fluorescence microscopy and colocalization quantification | *Schizosaccharomyces pombe* | Wang et al. 2023, *Nature Communications* — https://doi.org/10.1038/s41467-023-40530-4 | (pqac-00000008) |
| localization/quant data | **S. pombe-specific:** Wang et al. discuss Atg2 at the highly curved phagophore rim; the reported yeast phagophore rim diameter is about **15–17 nm**, consistent with Atg2 acting at extreme membrane curvature. | Ultrastructural interpretation integrated with localization data | *Schizosaccharomyces pombe* | Wang et al. 2023, *Nature Communications* — https://doi.org/10.1038/s41467-023-40530-4 | (pqac-00000009) |
| localization/partner | **S. pombe-specific review:** Atg2 is recruited to the PAS, and Atg18a promotes PAS targeting of Atg2; deletion of atg1 or atg2 restricts Atg9 and Ctl1 localization to the PAS. | Review synthesis of fluorescence localization/genetic studies | *Schizosaccharomyces pombe* | Xu & Du 2022, *Cells* — https://doi.org/10.3390/cells11071086 | (pqac-00000001, pqac-00000002, pqac-00000005, pqac-00000035) |
| function/localization | **Non-S. pombe / inferred:** Current consensus model is that ATG2/Atg2 is a rod-like lipid transfer protein and tether at phagophore-ER membrane contact sites, with an N-terminal ER-associated lipid-transfer module and C-terminal phagophore-binding region acting with Atg9 and Atg18/WIPI proteins. | Review of structural, biochemical, and cell-biological studies | Mainly budding yeast and mammalian systems; **inferred to S. pombe by conservation** | Duarte & Reggiori 2023, *Contact* — https://doi.org/10.1177/25152564231183898 | (pqac-00000013, pqac-00000016, pqac-00000017, pqac-00000030) |
| partner/function | **Non-S. pombe / inferred:** ATG2 works cooperatively with ATG9, which acts as a lipid scramblase; the combined model is that ATG2 transfers lipids into the phagophore while ATG9 equilibrates lipids across leaflets to support membrane expansion. | Review of recent cryo-EM, biochemical reconstitution, and genetics | Yeast and mammalian systems; **inferred to S. pombe by conservation** | Duarte & Reggiori 2023, *Contact* — https://doi.org/10.1177/25152564231183898; Choi et al. 2024, *Autophagy* — https://doi.org/10.1080/15548627.2024.2384349 | (pqac-00000026, pqac-00000027, pqac-00000025) |
| function/localization | **Non-S. pombe / inferred:** Budding-yeast Atg2-Atg18 tethers pre-autophagosomal membranes to the ER; Atg2 has membrane-binding regions at both ends, and loss of the complex blocks isolation membrane formation despite PAS accumulation of other Atg proteins. | Primary mechanistic study using mutagenesis, in vitro liposome tethering, PAS/ER localization assays | *Saccharomyces cerevisiae*; **mechanistic inference for S. pombe homolog** | Kotani et al. 2018, *PNAS* — https://doi.org/10.1073/pnas.1806727115 | (pqac-00000015) |
| partner/localization | **Non-S. pombe / inferred:** Atg9 helps establish Atg2-dependent ER-phagophore contact sites and confines Atg2 to phagophore extremities; disrupting Atg2-Atg9 interaction causes abnormal Atg2/ER-contact distribution and severe autophagy defects. | Primary mechanistic study with Atg2 point mutants, localization analysis, and ultrastructure | *Saccharomyces cerevisiae*; **mechanistic inference for S. pombe homolog** | Gómez-Sánchez et al. 2018, *Journal of Cell Biology* — https://doi.org/10.1083/jcb.201710116 | (pqac-00000019) |


*Table: This table compiles organism-specific evidence for Schizosaccharomyces pombe Atg2/mug36 and separates it from mechanistic inferences drawn from conserved Atg2 studies in other systems. It is useful for distinguishing direct annotation evidence from broader family-level functional models.*