| Category | Evidence summary | Key references with DOI/URL and publication date | Citation IDs |
|---|---|---|---|
| Identity/domains | **Verified target:** human **USO1** encodes **general vesicular transport factor p115** (also called p115/USO1), a Golgi/ER-Golgi tethering factor. Structural evidence from homolog work shows an **N-terminal globular head with armadillo-repeat/α-solenoid architecture** and a long **coiled-coil tail**; human-focused studies and reviews describe p115 as a **dimer** with N-terminal head and coiled-coil tail. **Note:** direct domain-resolution evidence here is mainly from yeast/fungal homologs and review synthesis, not a new 2023–2024 human structure. (pqac-00000010, pqac-00000016) | Heo Y et al. *Sci Rep* (2020), doi:10.1038/s41598-020-66480-1, https://doi.org/10.1038/s41598-020-66480-1, published Jun 2020; Yakunin I. PhD thesis (2023), doi:10.17863/cam.93885, https://doi.org/10.17863/cam.93885, published Feb 2023 | (pqac-00000010, pqac-00000016) |
| Core molecular function | **Human evidence:** p115/USO1 is a **Golgi vesicle tether** required for **ER-to-Golgi/early secretory trafficking**, vesicle docking, and secretion efficiency; recent human-cell work also supports direct binding of p115 to **Sec16A**, an ER exit site organizer, linking p115 to early secretory pathway organization. **Homolog evidence:** 2023 fungal work argues the **globular head directly binds SNAREs** and that long-range coiled-coil tethering may be partly dispensable, emphasizing a key role in **SNARE regulation/fusion competence**. (pqac-00000000, pqac-00000001, pqac-00000002) | Yakunin IG et al. bioRxiv preprint, doi:10.1101/2025.10.16.682774, https://doi.org/10.1101/2025.10.16.682774, posted Oct 2025; Bravo-Plaza I et al. *eLife* (2023), doi:10.7554/eLife.85079, https://doi.org/10.7554/elife.85079, published May 30 2023 | (pqac-00000000, pqac-00000001, pqac-00000002) |
| Key interaction partners | **Human-supported/reviewed partners:** **RAB1A** binds the N-terminus; **GM130** binds p115 at its N-terminus in a mitotically regulated manner; p115 also interacts with **giantin** at the C-terminus and with cis-Golgi **SNAREs** including **Sec22b, Bet1, GOSR2, syntaxin-5** in proposed SNARE-assembly/fusion models. **Human disease/pathogen context:** Legionella effector **LegA15** physically hijacks host p115. **Homolog support:** fungal/yeast studies support direct binding to Bet1/Bos1/Sec22-family SNAREs and recruitment dependence on Rab1/golgin systems. (pqac-00000008, pqac-00000016, pqac-00000007) | Chen T-T et al. *Sci Adv* (2022), doi:10.1126/sciadv.add7945, https://doi.org/10.1126/sciadv.add7945, published Dec 16 2022; Yakunin I. PhD thesis (2023), doi:10.17863/cam.93885, https://doi.org/10.17863/cam.93885, published Feb 2023; Bravo-Plaza I et al. bioRxiv (2022), doi:10.1101/2022.11.30.518472, https://doi.org/10.1101/2022.11.30.518472, posted Dec 2022 | (pqac-00000008, pqac-00000016, pqac-00000007) |
| Subcellular localization | **Human evidence/review:** p115 localizes to the **ERGIC and cis-Golgi**, associates with Golgi membranes in a **Rab1-dependent** manner, and functions at the **ER–Golgi interface**; recent human-cell work also links it to **ER exit sites** via Sec16A. **Homolog evidence:** fungal Uso1 cycles on early Golgi/ER-Golgi puncta. (pqac-00000000, pqac-00000001, pqac-00000002) | Yakunin IG et al. bioRxiv preprint, doi:10.1101/2025.10.16.682774, https://doi.org/10.1101/2025.10.16.682774, posted Oct 2025; Bravo-Plaza I et al. *eLife* (2023), doi:10.7554/eLife.85079, https://doi.org/10.7554/elife.85079, published May 30 2023 | (pqac-00000000, pqac-00000001, pqac-00000002) |
| Pathways/processes | USO1/p115 functions in the **early secretory pathway**, especially **COPII-derived ER-to-Golgi transport**, **vesicle tethering/docking**, and likely **cis-SNARE complex assembly/fusion**. In broader cell-biology/immune reviews, Golgi tethers including p115 are discussed as supporting **cytokine secretion** and Golgi-dependent innate immune signaling logistics, but this is contextual rather than USO1-specific mechanistic proof. (pqac-00000010, pqac-00000016, pqac-00000012) | Heo Y et al. *Sci Rep* (2020), doi:10.1038/s41598-020-66480-1, https://doi.org/10.1038/s41598-020-66480-1, published Jun 2020; Yakunin I. PhD thesis (2023), doi:10.17863/cam.93885, https://doi.org/10.17863/cam.93885, published Feb 2023; Mărunțelu I et al. *Int J Mol Sci* (2024), doi:10.3390/ijms25074120, https://doi.org/10.3390/ijms25074120, published Apr 8 2024 | (pqac-00000010, pqac-00000016, pqac-00000012) |
| Regulation/PTMs | **Human review evidence:** the **GM130–p115 interaction is blocked by Cdk1 phosphorylation of GM130 S37 during mitosis**, indicating cell-cycle regulation of p115 tethering. **Human phosphoproteomics:** **USO1 Ser48** was reported in RA synovial phosphoproteomic analysis as inversely correlated with ESR, suggesting regulated phosphorylation in disease tissue, but this is associative and not mechanistically assigned to trafficking. (pqac-00000016, pqac-00000009) | Yakunin I. PhD thesis (2023), doi:10.17863/cam.93885, https://doi.org/10.17863/cam.93885, published Feb 2023; Çubuk C et al. *Arthritis Res Ther* (2024), doi:10.1186/s13075-024-03351-4, https://doi.org/10.1186/s13075-024-03351-4, published Jun 2024 | (pqac-00000016, pqac-00000009) |
| Disease/clinical associations | **Cancer:** in human HCC, a tumor-associated isoform **USO1-T** correlates with poorer prognosis, promotes aggressive behavior, causes **Golgi unstacking**, and accelerates trafficking from ER to Golgi/plasma membrane; modeling suggests weakened dimerization/GM130 tethering and involvement of **ERK** and **GRASP65**. Additional literature summaries link USO1/p115 to colon cancer, gastric cancer, multiple myeloma, NSCLC, and leukemia vulnerability/fusions, though quantitative details are limited in the available snippets. **Infection:** Legionella **LegA15** hijacks host p115, causing Golgi fragmentation and altered lipid-droplet homeostasis. (pqac-00000013, pqac-00000014, pqac-00000015, pqac-00000008) | Yoon S et al. *Carcinogenesis* (2021), doi:10.1093/carcin/bgab067, https://doi.org/10.1093/carcin/bgab067, published Jul 22 2021; Chen T-T et al. *Sci Adv* (2022), doi:10.1126/sciadv.add7945, https://doi.org/10.1126/sciadv.add7945, published Dec 16 2022 | (pqac-00000013, pqac-00000014, pqac-00000015, pqac-00000008) |
| Recent developments 2023-2024 | **2023:** homolog-based mechanistic work showed the **Uso1/p115 globular head directly binds SNAREs** and can sustain essential function without the coiled-coil tether, sharpening the model from “long tether” to **SNARE-regulatory tether/fusion factor**. **2024:** Golgi/innate-immunity review highlights p115 among Golgi tethers relevant to secretory and immune processes; RA phosphoproteomics identified **USO1 Ser48** as a disease-associated phosphosite. **Caveat:** among retrieved items, truly human USO1-specific primary mechanistic advances in 2023–2024 were limited. (pqac-00000002, pqac-00000012, pqac-00000009) | Bravo-Plaza I et al. *eLife* (2023), doi:10.7554/eLife.85079, https://doi.org/10.7554/elife.85079, published May 30 2023; Mărunțelu I et al. *Int J Mol Sci* (2024), doi:10.3390/ijms25074120, https://doi.org/10.3390/ijms25074120, published Apr 8 2024; Çubuk C et al. *Arthritis Res Ther* (2024), doi:10.1186/s13075-024-03351-4, https://doi.org/10.1186/s13075-024-03351-4, published Jun 2024 | (pqac-00000002, pqac-00000012, pqac-00000009) |
| Quantitative data points | **Homolog quantitative data:** fungal Uso1 puncta half-life ~**60 s**; Pearson colocalization with GeaA/Gea1,2 **0.52 ± 0.06 (n=16)** and with RAB1 **0.61 ± 0.07 (n=20)**. **Human/pathogen quantitative data:** LegA15 interactome identified host p115/USO1 with **62 unique peptides** in MS. **Human trafficking assay framework:** HCC study quantified VSVG trafficking as mean % cells ± SEM with **n=5–8 fields, 10–50 cells/field**, but exact values were not in the available snippet. **Human interaction assay parameters (preprint):** RUSH assay used **1 mM biotin**, **35 min** progression, **3 biological repeats**. (pqac-00000002, pqac-00000004, pqac-00000020, pqac-00000017, pqac-00000019) | Bravo-Plaza I et al. *eLife* (2023), doi:10.7554/eLife.85079, https://doi.org/10.7554/elife.85079, published May 30 2023; Bravo-Plaza I et al. bioRxiv (2022), doi:10.1101/2022.11.30.518472, https://doi.org/10.1101/2022.11.30.518472, posted Dec 2022; Chen T-T et al. *Sci Adv* (2022), doi:10.1126/sciadv.add7945, https://doi.org/10.1126/sciadv.add7945, published Dec 16 2022; Yoon S et al. *Carcinogenesis* (2021), doi:10.1093/carcin/bgab067, https://doi.org/10.1093/carcin/bgab067, published Jul 22 2021; Yakunin IG et al. bioRxiv preprint, doi:10.1101/2025.10.16.682774, https://doi.org/10.1101/2025.10.16.682774, posted Oct 2025 | (pqac-00000002, pqac-00000004, pqac-00000020, pqac-00000017, pqac-00000019) |


*Table: This table summarizes supported functional annotation for human USO1/p115 (UniProt O60763), separating direct human evidence from inference based on yeast/fungal homologs. It highlights function, localization, partners, disease links, and the strongest quantitative findings available from the gathered evidence.*