# ATG14 notes

## 2026-06-02 review setup

- Started review from fetched UniProt/GOA-derived stub. ATG14 is a Beclin 1-associated autophagy factor and PI3KC3-C1 subunit; the UniProt record states that it is "required for both basal and inducible autophagy", determines localization of the autophagy-specific PI3-kinase complex PI3KC3-C1, enhances PIK3C3 activity in a BECN1-dependent manner, and promotes STX17/SNAP29/VAMP8-dependent autophagosome-endolysosome fusion [UniProt:Q6ZNE5].
- Key early complex evidence: human Atg14 and UVRAG form mutually exclusive Beclin 1/Vps34 complexes; Atg14 localizes to autophagic isolation membranes and Atg14 silencing suppresses autophagosome formation [PMID:18843052 "Atg14 is present on autophagic isolation membranes"; PMID:18843052 "Silencing of human Atg14 in HeLa cells suppresses autophagosome formation"].
- Barkor/Atg14L was identified as an autophagy-specific Beclin 1/class III PI3K factor; depletion reduces autophagy and autophagosome formation, whereas overexpression activates autophagy and increases autophagosomes [PMID:19050071 "Elimination of Barkor expression by RNA interference compromises starvation- and rapamycin-induced lipidation of LC3 and autophagosome formation"; PMID:19050071 "Overexpression of Barkor leads to autophagy activation"].
- Atg14L and UVRAG bind Beclin 1 mutually exclusively; Atg14L localizes at ER, isolation membranes, autophagosomes, and unidentified puncta, and Atg14L knockout caused defective autophagosome formation [PMID:19270696 "Atg14L and UVRAG bind to Beclin 1 in a mutually exclusive manner"; PMID:19270696 "Knockout of Atg14L in mouse ES cells caused a defect in autophagosome formation"].
- ER targeting evidence supports phagophore/ER-membrane localization: ATG14L cysteine repeats are required for ER localization and autophagosome formation, and the BATS domain is important for targeting the PI3K complex to the ER and autophagosome biogenesis [PMID:20713597 "Autophagy requires endoplasmic reticulum targeting of the PI3-kinase complex via Atg14L"].
- The C-terminal BATS domain targets Barkor/Atg14L to PtdIns(3)P-rich autophagic membranes and is required for PI3KC3 recruitment and autophagy stimulation [PMID:21518905 "PI3KC3 recruitment and autophagy stimulation by Barkor/Atg14(L) require the BATS domain"].
- Structural and interaction studies place ATG14 as the autophagy-specific organizer of the Beclin 1-VPS34/PIK3C3 complex, supporting class III PI3K complex and protein-membrane adaptor/regulator annotations rather than generic protein binding [PMID:22314358 "Atg14L-containing complex is primarily involved in early stage autophagosome formation"; PMID:25490155 "Architecture and dynamics of the autophagic phosphatidylinositol 3-kinase complex"].
- ATG14 has a later autophagosome fusion role: it binds the STX17-SNAP29 t-SNARE complex on autophagosomes, primes it for VAMP8 interaction, and promotes autophagosome-endolysosome fusion [PMID:25686604 "ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes"; UniProt:Q6ZNE5].
- BECN2 also interacts with ATG14 through a metastable coiled-coil to mediate autophagy, consistent with ATG14 acting as a PI3KC3-C1/BECN-family adaptor rather than only as a generic binding protein [PMID:28218432].
- Falcon deep research requested for ATG14 as part of the full review process.
- Falcon deep research timed out after the configured 600 second limit and did not produce `ATG14-deep-research-falcon.md`; final review therefore relies on the cached UniProt, GOA, Reactome, and publication evidence above.

## Description cleanup note

The YAML `description` field was revised to keep it as a standalone biological summary. Project-specific curation framing moved here instead.

- Moved out of the YAML description: the Proteostasis Network framing emphasized ATG14 as an autophagy-initiation/autophagosome-maturation component rather than a generic protein-binding or class I PI3K/AKT signaling factor.

## Falcon deep research findings (2026-06-07)

The Falcon (Edison Scientific) report (`ATG14-deep-research-falcon.md`) was successfully generated (the prior 2026-06-02 timeout note is now superseded). It is consistent with the completed review and adds mostly mechanistic/regulatory detail rather than new core functions. Key points:

- NEW (regulation): ULK1 phosphorylates ATG14L at Ser29, and this phosphorylation is required for VPS34/PI3KC3-C1 activation and PI3P production at autophagosome formation sites; phospho-Ser29 is abolished in ULK1/2 double-knockout or kinase-dead ULK1 cells and restored by WT ULK1 under starvation [PMID:39169022 "the ULK1 palmitoylated enhances the phosphorylation of ATG14L, which is required for activating PI3-Kinase and producing phosphatidylinositol 3-phosphate"; Tabata et al. 2024 Nat Commun, doi:10.1038/s41467-024-51402-w]. This adds an upstream ULK1-kinase->ATG14 site-specific link not previously cited in the review, complementing existing ATG14-dependent BECN1-phosphorylation annotations. The existing review already supports positive/negative regulation of protein phosphorylation involving ATG14; this adds that ATG14 is itself a ULK1 substrate.
- NEW (upstream control, provisional/mechanistic): ULK1 palmitoylation by ZDHHC13 promotes ULK1 translocation to autophagosome formation sites and is required for ULK1->ATG14L Ser29 phosphorylation; 2-bromopalmitate suppresses starvation-induced ATG14 Ser29 phosphorylation [PMID:39169022, Tabata et al. 2024]. This is ULK1/ZDHHC13 biology upstream of ATG14, not a direct ATG14 molecular function - do NOT add as an ATG14 annotation.
- CONFIRMS (complex/architecture): PI3KC3-C1 is a ~360 kDa 1:1:1:1 heterotetramer (VPS34/PIK3C3 : VPS15/PIK3R4 : BECN1 : ATG14) with only ~11% catalytic mass, reinforcing ATG14's non-enzymatic regulatory/targeting role; mutually exclusive with UVRAG-containing PI3KC3-C2 [Chen & Hurley 2025 J Biol Chem, doi:10.1016/j.jbc.2025.110391, PMID:40543587]. Matches existing GO:0035014 / GO:0034271 annotations.
- CONFIRMS (domain/localization): C-terminal BATS domain (~last 80 aa, ~19-aa amphipathic helix) is a membrane-curvature sensor preferring highly curved PI3P/PI(4,5)P2-enriched isolation membranes; N-terminal cysteine-repeat mediates ER targeting; co-localizes with DFCP1/ATG16L1 at omegasomes [Liu et al. 2023 Cells, doi:10.3390/cells12081132 - review]. Already captured by existing BATS/omegasome/phagophore annotations.
- CONFIRMS (downstream function): ATG14-dependent PI3KC3-C1 activity supports WIPI2/ATG2A recruitment and LC3 lipidation, and complex II cannot functionally substitute [Brier et al. 2019, doi:10.1091/mbc.e18-11-0743, PMID:30540564 (not cached)]. Consistent with existing autophagosome-assembly core function.
- PROVISIONAL (disease, low-confidence): Open Targets lists association-level links (neurodegeneration, COVID-19, dengue, lysosomal storage disease); the report explicitly flags these as association/inference, not causal. No ATG14-targeted clinical trials identified. NOT used to change any annotation.
- Pharmacology context (provisional): VPS34 inhibitors and a reported Beclin1-ATG14L interaction inhibitor are discussed as autophagy-initiation tool compounds [Lee et al. 2024 Biomol Ther, doi:10.4062/biomolther.2024.094 - review]. Tool-compound context only.

Action taken: added the two most citable, ATG14-relevant primary/key sources (Tabata 2024 PMID:39169022; Chen & Hurley 2025 PMID:40543587) to the review `references:` as statement-only findings (full_text_unavailable), plus one suggested question and one suggested experiment about the ULK1->ATG14 Ser29 axis. Review-only sources (Liu 2023, Lee 2024) and the non-resolved/uncached Brier paper are kept in notes only. No existing annotation `action` was changed - all Falcon findings either confirm existing calls or are upstream/association-level context.