tbc1d14 encodes a TBC (Tre2-Bub2-Cdc16) Rab-GAP-domain protein of the vertebrate TBC1D14 orthology group. In vertebrates it acts as a non-catalytic regulator of membrane traffic between recycling endosomes and the early Golgi. Characterised mammalian TBC1D14 binds the GTP-bound forms of RAB11A and RAB11B, but it shows no detectable GAP activity toward RAB11 or a broad panel of other Rabs, and it behaves as a RAB11 effector. Its N-terminal region binds the TRAPPIII tethering complex through TRAPPC8, which is needed for RAB1 activation. The protein also binds the autophagy kinase ULK1. TBC1D14 sits on RAB11-positive recycling endosomes and moves toward the Golgi under amino-acid starvation. It controls the supply of recycling-endosome membrane and the cycling of ATG9 to sites of autophagosome formation, and so acts as a negative regulator of starvation-induced macroautophagy. The Atlantic cod protein shares this architecture: an N-terminal disordered region, a TRAPP-binding segment aligned to the mammalian region, a coiled coil, and a C-terminal TBC domain (residues 388-596) that keeps the arginine- and glutamine-finger residues.
Summary: TreeGrafter transfer from PANTHER node PTN009208344. The cod protein was placed in PTHR47219:SF15 (the TBC1D12 subfamily) and inherits GAP activity from a deep node seeded by RABGAP1/RABGAP1L. The re-review tree puts cod tbc1d14 inside the vertebrate TBC1D14 clade, not with TBC1D12, so the correct comparator is TBC1D14. Human TBC1D14 binds GTP-locked RAB11A and RAB11B. In a screen of 47 [32P]GTP-loaded Rabs, recombinant TBC1D14 showed no detectable GAP activity, and the authors describe it as having no GAP activity. The arginine- and glutamine-finger positions are retained in the cod sequence (R457/Q493). Keeping these residues does not show catalysis.
Reason: The direct experimental test on the ortholog is negative: no GAP activity toward RAB11 or 46 other Rabs. The ortholog's function is that of a Rab11 effector and TRAPPIII scaffold. The term reaches cod only through a subfamily placement that the phylogeny does not support. PAINT does propagate GTPase activator activity to human TBC1D14 from a deep TBC-family node, and a substrate outside the tested panel cannot be ruled out formally, so this is recorded as an over-annotation rather than a removal.
We then performed a GAP assay screen using a panel of 47 Rabs loaded with [32P]GTP but were unable to detect GAP activity with either recombinant GST-TBC1D14
Summary: ARBA rule-based location. In GO, the only route from TBC1D14 biology to vacuole is autophagosome (GO:0005776), which is_a vacuole. Mammalian TBC1D14 is mainly on recycling endosomes and moves to the Golgi on starvation. Its contact with autophagosome-forming membrane comes from overexpressed protein on ULK1-positive tubules. No lysosomal or vacuolar residence has been reported.
Reason: Vacuole is not where the ortholog has been seen. The documented compartments are recycling endosome and Golgi, and residence on the autophagosome itself is weakly supported. The ARBA rule gives no protein-specific evidence.
Summary: ARBA rule-based process. The mammalian ortholog regulates membrane traffic from RAB11-positive recycling endosomes. The proposed model is a constitutive step from peripheral recycling endosomes to the early Golgi, mediated by TRAPPIII and RAB1, that maintains the cycling ATG9 pool. More specific GO transport terms (e.g. GO:0042147 retrograde transport, endosome to Golgi) are not annotated to the experimentally studied ortholog. The precise transport step is a proposed model, not a measured transport reaction.
Reason: The term is correct and is as specific as the evidence allows. TBC1D14 is part of the membrane-trafficking machinery: it binds RAB11, recruits TRAPPIII and is required for RAB1 activation. The exact transport step it carries out is not established well enough to justify a narrower process term.
In support of an interaction of TBC1D14 and TRAPPIII, it has been shown that exchange between the transferrin/RAB11‐positive RE and the RAB1‐positive ERGIC/early Golgi can occur
Summary: ARBA rule-based function. The term is true but uninformative. The enzyme partners documented for the ortholog are the small GTPases RAB11A/B, bound in the GTP-loaded form, and the autophagy kinase ULK1. Both are better described by specific descendants of enzyme binding: small GTPase binding (GO:0031267, already carried by this gene) and protein kinase binding (GO:0019901).
Reason: The term is correct but too general. Replace it with the specific supported descendants small GTPase binding (RAB11) and protein kinase binding (ULK1).
Summary: TreeGrafter transfer. It arrives through the SF15 placement, but the function is independently supported for the true ortholog group. Human TBC1D14 binds GTP-locked RAB11A and RAB11B selectively in a yeast two-hybrid screen of GTP-locked Rabs. RAB11 binding recruits the protein to recycling endosomes, and loss of RAB11 prevents TBC1D14-induced tubulation. The cod protein falls in the TBC1D14 clade and keeps the TBC domain through which Rab binding occurs. The more specific Rab GTPase binding term (GO:0017137) is obsolete, so small GTPase binding is the appropriate term.
Reason: Binding of active RAB11 is the best-characterised molecular activity of TBC1D14 orthologs, and the cod protein is a phylogenetic member of that orthology group.
Summary: ARBA rule-based location. It is correct but general. The ortholog's documented compartment is the RAB11- and transferrin receptor-positive recycling endosome, and GO:0055037 recycling endosome is a descendant of cytoplasmic vesicle (via endosome and intracellular vesicle). PAINT places recycling endosome on the TBC1D14 clade (PTN000538677), which the cod protein belongs to by the re-review tree. Cod did not receive that IBA because PANTHER mis-assigned it to SF15.
Reason: Replace with the more specific recycling endosome, the compartment supported by the ortholog data.
Summary: Proposed new annotation. PAINT placed regulation of autophagosome assembly on node PTN008586039, seeded by human TBC1D14 IMP data, which covers the TBC1D14 clade. The cod protein belongs to that clade by phylogeny but was routed by TreeGrafter through SF15 and so did not inherit the term. TBC1D14 does part of the regulatory work itself: it binds RAB11 and TRAPPIII and is required for RAB1 activation and ATG9 cycling. This is the role the curators assigned, not a downstream phenotype.
Reason: The term matches the ortholog's established role and the PAINT node that covers the TBC1D14 clade. It is missing in cod only because of a subfamily mis-assignment shown by the re-review tree.
We show here TBC1D14 acts as a negative regulator of autophagy by modulating the contribution of both RE and Golgi membranes to the growing autophagosome through its interaction with Rab11 and TRAPPIII.
the two cod tbc1d14 models fall inside the vertebrate TBC1D14 clade
Core Functions
Binds GTP-bound RAB11 as an effector rather than a GAP. This binding places the protein on RAB11-positive recycling endosomes, where it scaffolds the TRAPPIII complex and supports RAB1 activation at the recycling endosome to early Golgi interface. Inferred from the characterised mammalian ortholog. The cod protein falls in the TBC1D14 orthology clade.
Q: Should PANTHER move teleost and coelacanth tbc1d14 from PTHR47219:SF15 (TBC1D12) to SF21 (TBC1D14)? A distance tree puts them in the TBC1D14 clade, and the SF15 placement routes TBC1D12/RABGAP1 node annotations to them while blocking the TBC1D14-clade PAINT terms.
Q: Does cod tbc1d14 retain any GAP activity toward a Rab outside the 47-Rab panel tested for the human ortholog, given that its arginine and glutamine fingers are intact?
Q: Is the non-conserved 48-residue C-terminal tail of the A0A8C5FPT8 model supported by transcript evidence, or is it a read-through artefact relative to the A0A8C5FCB4 model?
Suggested Experiments
Experiment: Pulldown of recombinant cod tbc1d14 with GTP- and GDP-locked cod rab11a/rab11b, and co-immunoprecipitation with trappc8, to test whether the effector and TRAPPIII-scaffold interactions are conserved in teleosts.
Hypothesis: Cod tbc1d14 binds active Rab11 and TRAPPIII as the mammalian ortholog does.
Experiment: RT-PCR or long-read sequencing across the 3' end of ENSGMOG00000018292 to determine which C-terminal exon (conserved ...QKDQERSSPVLRR versus the A0A8C5FPT8 tail) is used in vivo.
Hypothesis: The conserved C-terminus of the A0A8C5FCB4 model is the predominant product.
External Prediction Reviews
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Atlantic cod tbc1d14 falls inside the vertebrate TBC1D14 clade by sequence phylogeny, despite its PANTHER SF15 (TBC1D12-like) placement. Human TBC1D14 carries an experimentally supported, partial autophagosome localization that PAINT places on the TBC1D14-clade node, so the single ProtNLM2 autophagosome prediction is a supported, peripheral localization transfer; the ortholog's predominant compartments are recycling endosomes and, on starvation, the Golgi.
Prediction method: ProtNLM2 · Version: UniProt 2024_06 pilot
Review rationale: Autophagosome is not among the cod gene's GOA terms; its only related annotation is the broader ARBA vacuole term (autophagosome is_a vacuole per OLS4), so the prediction is novel and more specific. The re-review sequence tree places cod tbc1d14 inside the vertebrate TBC1D14 clade, separate from TBC1D12, which makes the PANTHER SF15 assignment a subfamily mis-routing; the cod protein retains the TBC1D14 architecture and has its strongest phmmer match to reviewed bovine TBC1D14. Human TBC1D14 has an IDA autophagosome annotation from PMID:22613832 (partial colocalization of endogenous protein with LC3), and PAINT placed the same term on the TBC1D14-clade node; the human gene review keeps both rows as correct but non-core. This is a justified orthology transfer of experimentally grounded evidence. The localization is peripheral and partial: TBC1D14 acts mainly from recycling endosomes and the Golgi to regulate autophagosome formation, and no fish experiment addresses it, so it should not be read as constitutive residence.
Supporting Evidence:
file:GADMO/A0A8C5FPT8/A0A8C5FPT8-uniprot.txt: "ID A0A8C5FPT8_GADMO Unreviewed; 709 AA. ... DR InterPro; IPR000195; Rab-GAP-TBC_dom. ... DR PANTHER; PTHR47219:SF15; TBC1 DOMAIN FAMILY MEMBER 12 ISOFORM X1; 1. ... FT DOMAIN 388..596 ... FT /note="Rab-GAP TBC""
PMID:22613832: "TBC1D14 binds activated Rab11 but is not a GAP for Rab11"
PMID:22613832: "Endogenous TBC1D14 also shows partial colocalization with LC3"