| Claim | Key evidence statement (paraphrased) | Evidence type | Source (short citation with year) | Publication date | URL/DOI | Context ID for citation |
|---|---|---|---|---|---|---|
| Identity | SwissProt/UniProt accession **P15476** is explicitly listed as **“Patatin B1 precursor, Solanum tuberosum”**, confirming the target is potato Patatin-B1/PATB1 rather than a different similarly named protein. | Primary/database-linked | James et al. 1994 | Aug 1994 | https://doi.org/10.1002/pro.5560030822 | (pqac-00000007) |
| Family / precursor status | Potato patatins are mature proteins of ~**360 aa** synthesized with an **N-terminal 23-aa signal peptide**, consistent with UniProt’s “precursor” annotation and trafficking through the endomembrane system. | Review synthesizing primary literature | Shewry 2003 | Jun 2003 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000003, pqac-00000009) |
| Localization | Immunocytochemistry showed patatin is localized **mainly in vacuoles** of potato tubers and induced leaves; **cell walls and intercellular space lacked detectable patatin**. | Primary | Sonnewald et al. 1989 | May 1989 | https://doi.org/10.1007/BF00393192 | (pqac-00000020, pqac-00000021) |
| Glycoprotein / trafficking | Patatin is a **glycoprotein** that becomes **N-glycosylated**; glycosylation plus vacuolar localization support **ER/Golgi trafficking** before deposition in storage vacuoles. | Primary + review | Sonnewald et al. 1989; Shewry 2003 | May 1989; Jun 2003 | https://doi.org/10.1007/BF00393192 ; https://doi.org/10.1093/aob/mcg084 | (pqac-00000020, pqac-00000009) |
| Molecular size / abundance | Patatin is a major potato tuber protein of about **40–45 kDa** and can account for roughly **40% of soluble tuber protein**; one summary table lists ~**40,000 Da** and ~**40%** abundance. | Review/table summary | Shewry 2003 | Jun 2003 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000009, pqac-00000016) |
| Isoform heterogeneity | Patatin exists as multiple glycoforms/isoforms; review data describe masses around **40,400–41,600 Da**, and other summaries report **40.6, 41.8, 42.9 kDa** isoforms in tubers. | Review / thesis-style summary | Shewry 2003; Overeem 2017 | Jun 2003; 2017 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000009, pqac-00000011) |
| Enzymatic function | Patatin has **lipid acyl hydrolase / phospholipase A-like activity** rather than being only a passive storage protein; early biochemical work identified deacylation of several lipid classes as patatin-dependent activity. | Review synthesizing primary literature | Shewry 2003 | Jun 2003 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000009) |
| Substrate range | Reported substrates include **mono- and diacylphospholipids, galactolipids/galactosyl diglycerides, mono- and diglycerides**, indicating broad acyl-hydrolase activity toward membrane and neutral lipids. | Review synthesizing primary literature | Shewry 2003; Overeem 2017 | Jun 2003; 2017 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000009, pqac-00000011) |
| PLA2-like biochemical model | A recent systematic review describes patatins as **Ca2+-independent lipid acyl hydrolase / PLA2-like enzymes** with a **Ser–Asp catalytic dyad**, hydrolyzing **phosphatidylcholine, phosphatidylethanolamine, lysophospholipids, and neutral acylglycerols**; this is strong family-level inference but not PATB1-specific experimentation. | Review (family-level inference) | Wu et al. 2025 | Dec 2025 | https://doi.org/10.3390/biology15010029 | (pqac-00000012, pqac-00000013) |
| Catalytic motif | Conserved patatin-domain catalytic architecture includes a **Gly-X-Ser-X-Gly** motif and **Ser–Asp dyad**, supporting classification of PATB1 as a patatin-family serine hydrolase. | Review (family-level inference) | Wu et al. 2025 | Dec 2025 | https://doi.org/10.3390/biology15010029 | (pqac-00000012, pqac-00000013) |
| Additional enzymatic activities | Patatin has also been reported to show **esterase** activity toward **PNP-laurate, PNC-acetate, α-/β-naphthyl acetate/laurate, phenyl acetate**, and some summaries include **β-1,3-glucanase** activity. | Review / summary | Shewry 2003; Isayenka 2020 | Jun 2003; 2020 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000016, pqac-00000008) |
| Tissue specificity / expression | Class I patatin genes are the main tuber-expressed forms, whereas class II transcripts are largely root-associated and are about **50–100-fold less abundant in tubers**. | Review synthesizing primary literature | Shewry 2003 | Jun 2003 | https://doi.org/10.1093/aob/mcg084 | (pqac-00000009) |
| Cellular compartment within tuber | Patatin is mainly present in **parenchyma cell vacuoles**; esterase staining in tuber sections co-localizes with parenchyma, matching the immunolocalization pattern. | Primary | Sonnewald et al. 1989 | May 1989 | https://doi.org/10.1007/BF00393192 | (pqac-00000020, pqac-00000021) |
| Biological role: storage | Patatin is the **major soluble storage protein** of potato tubers and is widely interpreted as a **nitrogen/carbon reserve protein** in addition to its enzymatic activities. | Primary + review | Sonnewald et al. 1989; Shewry 2003 | May 1989; Jun 2003 | https://doi.org/10.1007/BF00393192 ; https://doi.org/10.1093/aob/mcg084 | (pqac-00000020, pqac-00000009) |
| Biological role: defense / wound response | Reviews summarize evidence that patatin may contribute to **defense and wound responses** by releasing fatty acids from membranes, supplying precursors for **suberin/wax synthesis**, and inhibiting pests/pathogens such as **corn rootworm larvae** and **Phytophthora infestans** spores. | Review / summary | Isayenka 2020; Overeem 2017 | 2020; 2017 | N/A | (pqac-00000008, pqac-00000011) |
| Biological role: oxylipin-related signaling (indirect inference) | Patatin-like enzymes in tobacco are induced before **jasmonate/oxylipin accumulation** during pathogen response, supporting a broader plant-family model in which patatin-like phospholipases release fatty acids for defense signaling; this supports inference but is **not direct PATB1 evidence**. | Primary in related species | Dhondt et al. 2000 | Aug 2000 | https://doi.org/10.1046/j.1365-313X.2000.00802.x | (pqac-00000017) |
| Recent developments / applications | Recent work outside potato showed overexpression of a **patatin-like gene** in poplar improved **drought tolerance** and increased **cellulose content**; this demonstrates ongoing applied interest in patatin-family genes, but the result is **not specific to potato PATB1**. | Primary in another species | Georgieva et al. 2024 | 18 Oct 2024 | https://doi.org/10.3389/fpls.2024.1468905 | (pqac-00000022) |


*Table: This table compiles the main evidence supporting functional annotation of potato Patatin-B1 (PATB1; UniProt P15476), including identity verification, localization, enzyme activity, biological roles, and relevant quantitative details. It distinguishes direct potato evidence from broader patatin-family inference and recent cross-species developments.*