The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The Atlantic cod gene tbc1d14 (UniProt accession A0A8C5FPT8) encodes a Rab-GAP TBC domain-containing protein. While no direct experimental literature on this specific cod gene was identified in the current literature search, the protein's function can be reliably inferred from extensive studies of conserved TBC1D14 orthologs in mammalian systems, particularly human and mouse models. The Atlantic cod protein contains the characteristic Rab-GAP TBC domain (InterPro IPR000195, IPR035969, IPR050302; Pfam PF00566), establishing its membership in the TBC (Tre2-Bub2-Cdc16) family of Rab GTPase regulators (lamb2016tbc1d14regulatesautophagy pages 1-2, popovic2012rabgtpaseactivatingproteins pages 1-2).
TBC1D14 belongs to the TBC domain-containing protein family, a large family of proteins characterized by the presence of a conserved TBC domain (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 2-3). The TBC domain is approximately 200 amino acids in length and typically functions as a GTPase-activating protein (GAP) domain for Rab small GTPases (popovic2012rabgtpaseactivatingproteins pages 1-2). In general, TBC domain-containing proteins regulate Rab GTPases through a dual-finger catalytic mechanism, wherein conserved arginine (R-finger) and glutamine (Q-finger) residues within the TBC domain coordinate with the Rab-bound GTP molecule to accelerate GTP hydrolysis (chen2017crystalstructureof pages 1-2, popovic2012rabgtpaseactivatingproteins pages 1-2).
The TBC1D14 protein exhibits a modular domain architecture (lamb2016tbc1d14regulatesautophagy pages 3-5):
This modular organization allows TBC1D14 to serve as a scaffold protein that coordinates multiple protein-protein interactions involved in membrane trafficking and autophagy.
Despite containing a TBC domain typically associated with Rab-GAP activity, TBC1D14 does not function as a canonical GAP for RAB11. Instead, experimental evidence demonstrates that TBC1D14 binds to RAB11 and functions as a RAB11 effector rather than catalyzing GTP hydrolysis on RAB11 (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 14-17). This represents an important functional distinction: while TBC1D14 possesses the structural hallmarks of a Rab-GAP, it has evolved to serve primarily as a scaffolding and regulatory protein rather than an enzyme that directly inactivates Rab proteins (lamb2016tbc1d14regulatesautophagy pages 2-3).
The mechanism by which TBC1D14 interacts with RAB11 involves binding to the GTP-bound (active) form of RAB11, which recruits TBC1D14 to RAB11-positive recycling endosome membranes (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 2-3). This RAB11-TBC1D14 interaction is required for the formation of specific membrane trafficking intermediates.
A central molecular function of TBC1D14 is its ability to recruit the TRAPPIII tethering complex to specific cellular membranes (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 2-3). The interaction occurs through the N-terminal TRAPP-binding region (aa 120-223) of TBC1D14, which specifically binds to TRAPPC8, the mammalian ortholog of the yeast Trs85 subunit (lamb2016tbc1d14regulatesautophagy pages 7-10, lamb2016tbc1d14regulatesautophagy pages 12-14). TRAPPC8 is considered an autophagy-specific subunit that distinguishes the TRAPPIII complex from other TRAPP complexes (lamb2016tbc1d14regulatesautophagy pages 12-14).
Through its interaction with TRAPPC8, TBC1D14 mediates binding to the core TRAPP subunits, including TRAPPC4 and TRAPPC12, forming a functional TRAPPIII-like complex in mammalian cells (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 7-10). This represents the first clear evidence at the endogenous protein level for a mammalian TRAPPIII complex analogous to the yeast TRAPPIII involved in autophagy (lamb2016tbc1d14regulatesautophagy pages 12-14).
While TBC1D14 does not directly act as a GEF (guanine nucleotide exchange factor), it plays a critical role in facilitating RAB1 activation by positioning and recruiting the TRAPPIII complex, which serves as the GEF for RAB1 (lamb2016tbc1d14regulatesautophagy pages 10-12, lamb2016tbc1d14regulatesautophagy pages 7-10). Specifically:
This mechanism positions TBC1D14 as a spatial regulator that determines where and when RAB1 activation occurs, rather than as a direct enzymatic activator.
TBC1D14 exhibits a complex subcellular distribution, localizing to several distinct membrane compartments:
TBC1D14 localizes to RAB11-positive recycling endosomes, both in peripheral regions of the cell and in the juxtanuclear endocytic recycling compartment (ERC) (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 12-14). When overexpressed, TBC1D14 induces the formation of tubulated transferrin-positive recycling endosome structures, which can be visualized by loading cells with fluorescent transferrin (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 2-3). These tubulated structures are highly enriched in RAB11 and serve as a model system for studying TBC1D14 function in membrane trafficking.
Endogenous TBC1D14 also localizes to the Golgi stack, where it partially colocalizes with the cis-Golgi marker GM130, the small GTPase RAB1B, and TRAPP complex subunits such as TRAPPC4 (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 2-3). This Golgi localization positions TBC1D14 at a key intersection between the endocytic recycling pathway and the early secretory/biosynthetic pathway.
Notably, overexpression of TBC1D14 or its TRAPP-binding region causes fragmentation of the Golgi complex, disrupting the normal juxtanuclear organization of GM130-positive cisternae (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 7-10). This phenotype underscores the importance of TBC1D14 dosage and localization for maintaining Golgi integrity.
A particularly important finding is that TBC1D14-positive membranes can simultaneously harbor RAB11A, RAB1B, and TRAPPC4, indicating that TBC1D14 localizes to transport intermediates that bridge RAB11-positive recycling endosomes and RAB1-positive early Golgi/ERGIC (ER-Golgi intermediate compartment) membranes (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 14-17). These hybrid compartments are thought to represent sites where membrane identity transitions occur—specifically, where RAB11-positive membranes are converted to RAB1-positive membranes through a process coordinated by TBC1D14 and the TRAPPIII complex (lamb2016tbc1d14regulatesautophagy pages 14-17).
TBC1D14 functions as a negative regulator of macroautophagy (hereafter referred to as autophagy), a cellular self-degradation pathway essential for clearing damaged organelles, protein aggregates, and other cytoplasmic materials (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 2-3). The protein exerts this regulatory function through multiple mechanisms:
TBC1D14 regulates the contribution of membranes from RAB11-positive recycling endosomes to forming autophagosomes (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 2-3). Recycling endosomes have been identified as an important membrane source for autophagosome biogenesis, and TBC1D14 modulates this membrane supply. When TBC1D14 is overexpressed, it inhibits autophagy by disrupting the normal delivery of recycling endosome-derived membranes to autophagosome formation sites (lamb2016tbc1d14regulatesautophagy pages 2-3).
Overexpression of TBC1D14 or its TRAPP-binding region impairs the formation of early autophagy structures, including:
These effects demonstrate that TBC1D14 acts at an early step in the autophagy pathway, influencing the initial nucleation and expansion of the autophagosomal membrane rather than later maturation or fusion steps.
A particularly important and specific function of TBC1D14 is its role in regulating the trafficking of ATG9 (autophagy-related protein 9), the only multi-spanning transmembrane protein among the core autophagy machinery (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 12-14).
ATG9 normally cycles between the Golgi complex, recycling endosomes, and a specialized "ATG9 compartment" (lamb2016tbc1d14regulatesautophagy pages 12-14). This cycling is essential for delivering ATG9-containing vesicles to sites of autophagosome formation. TBC1D14, together with the TRAPPIII complex and RAB1, is required to maintain the proper cycling pool of ATG9 (lamb2016tbc1d14regulatesautophagy pages 14-17, lamb2016tbc1d14regulatesautophagy pages 12-14).
When TBC1D14 function is disrupted—either by overexpressing a dominant-negative TRAPP-binding region or by depleting TRAPPC8—the normal juxtanuclear accumulation of ATG9 is lost, and ATG9 becomes dispersed throughout the cell (lamb2016tbc1d14regulatesautophagy pages 12-14). This dispersion indicates that TBC1D14/TRAPPIII/RAB1 function is required for maintaining ATG9 at specific membrane compartments.
Remarkably, the effect of TBC1D14 and TRAPPIII on ATG9 trafficking is independent of ULK1, the primary autophagy-initiating kinase (lamb2016tbc1d14regulatesautophagy pages 12-14). While ULK1 is required for starvation-induced redistribution of ATG9 to peripheral compartments, the constitutive maintenance of ATG9 at the Golgi in fed cells depends on TBC1D14, TRAPPIII, and RAB1 (lamb2016tbc1d14regulatesautophagy pages 12-14). This indicates that TBC1D14 regulates a constitutive trafficking step that operates even in the absence of autophagy induction, maintaining a ready pool of ATG9 that can be rapidly mobilized when autophagy is activated.
Immunoisolation experiments have shown that TRAPPC8 and TRAPPC4 co-isolate with ATG9-positive membranes, both under fed and starved conditions (lamb2016tbc1d14regulatesautophagy pages 12-14). This physical association supports the model that TBC1D14 and the TRAPPIII complex directly regulate ATG9-containing vesicles, likely by promoting their trafficking between different membrane compartments.
Beyond its role in autophagy, TBC1D14 also participates in regulating the secretory pathway and maintaining Golgi integrity (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 7-10):
These findings indicate that TBC1D14 has pleiotropic effects on multiple membrane trafficking pathways, consistent with its localization to both endocytic recycling and early secretory compartments.
Integrating these findings, a comprehensive model emerges (lamb2016tbc1d14regulatesautophagy pages 14-17):
This model positions TBC1D14 as a molecular coordinator that links endocytic recycling, early secretory trafficking, and autophagy-related membrane dynamics.
Although TBC1D14 itself lacks demonstrated GAP activity toward RAB11, understanding the general mechanism of TBC domain-mediated Rab inactivation provides important context (chen2017crystalstructureof pages 1-2, popovic2012rabgtpaseactivatingproteins pages 1-2):
The fact that TBC1D14 does not exhibit GAP activity toward RAB11 despite containing a TBC domain suggests that either (1) the catalytic residues in TBC1D14's TBC domain are not optimally positioned or configured for RAB11, or (2) TBC1D14 may act as a GAP for a different, as-yet-unidentified Rab substrate. Alternatively, the TBC domain of TBC1D14 may have evolved to serve primarily a structural role in protein scaffolding rather than an enzymatic role.
The interaction between TBC1D14 and the TRAPPIII complex involves multiple subunits (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 7-10):
This architecture allows TBC1D14 to serve as a spatial regulator that recruits TRAPPIII GEF activity to specific membrane compartments defined by RAB11.
No experimental studies specifically examining the Atlantic cod tbc1d14 gene or protein were identified in the current literature search. This absence of species-specific data is a critical limitation that must be acknowledged. All functional assignments for the Atlantic cod protein are therefore inferred from conserved features and homology to well-studied mammalian orthologs.
The UniProt annotation for Atlantic cod TBC1D14 (A0A8C5FPT8) identifies the presence of a Rab-GAP TBC domain (IPR000195, IPR035969, IPR050302; Pfam PF00566). This domain annotation is based on sequence homology and is highly reliable for establishing membership in the TBC protein family. However, the specific substrate specificity, binding partners, and cellular functions in cod cells remain experimentally unvalidated.
Given the high evolutionary conservation of membrane trafficking machinery across vertebrates, it is reasonable to infer that Atlantic cod TBC1D14 likely participates in:
However, cod-specific functional nuances—such as potential roles in fish-specific physiological processes (e.g., adaptation to aquatic environments, temperature-dependent metabolism)—cannot be predicted from mammalian data alone.
To provide additional functional context, it is useful to briefly compare TBC1D14 with closely related TBC family members:
TBC1D12 is another RAB11-binding TBC protein identified in a systematic screen for recycling endosome-localized TBC proteins (oguchi2017tbc1d12isa pages 1-2). Like TBC1D14, TBC1D12:
- Colocalizes with transferrin receptor on recycling endosomes
- Interacts with active RAB11 through a middle region of the protein (not the TBC domain)
- Does not display RAB11-GAP activity in vitro
- Modulates neurite outgrowth in PC12 cells, a specialized RAB11-dependent cellular process
This parallel reinforces the concept that not all TBC domain-containing proteins function as canonical Rab-GAPs; some, including TBC1D14 and TBC1D12, have evolved to serve as RAB11 effectors with scaffolding and regulatory functions (oguchi2017tbc1d12isa pages 1-2).
TBC1D9B is a bona fide RAB11-GAP that, unlike TBC1D14, does exhibit GAP activity toward RAB11A (gallo2014tbc1d9bfunctionsas pages 1-2). TBC1D9B:
- Binds RAB11A, RAB11B, and RAB4A via its TBC domain in a nucleotide-dependent manner
- Accelerates GTP hydrolysis specifically on RAB11A (and RAB8A under limiting Mg²⁺ conditions)
- Regulates basolateral-to-apical transcytosis in polarized epithelial cells
The contrast between TBC1D9B (a true RAB11-GAP) and TBC1D14 (a RAB11 effector) highlights the functional diversity within the TBC protein family.
| Category | TBC1D14 feature | Specific details | Functional implication | Key evidence/citations |
|---|---|---|---|---|
| Gene/protein identity | Atlantic cod target from UniProt | UniProt A0A8C5FPT8 is annotated as Rab-GAP TBC domain-containing protein, gene tbc1d14, from Gadus morhua; direct species-specific literature was not found in the retrieved corpus, so functional interpretation relies on conserved TBC1D14 studies from other vertebrates plus the conserved Rab-GAP TBC domain annotation | Supports cautious homology-based functional inference rather than direct cod-specific experimental assignment | (lamb2016tbc1d14regulatesautophagy pages 1-2, popovic2012rabgtpaseactivatingproteins pages 1-2) |
| Domain organization | C-terminal TBC domain | TBC1D14 has a typical TBC-domain protein architecture with the TBC domain at the C-terminus; one construct spanning aa 224–669 includes the C-terminal region and the putative TBC domain from aa 411–611 | Establishes membership in the TBC Rab-regulator family and suggests potential Rab-related regulatory capacity | (lamb2016tbc1d14regulatesautophagy pages 3-5) |
| Domain organization | TRAPP-binding region (TBR) | A 103 aa N-terminal region, aa 120–223, is sufficient for TRAPP interaction and is termed the TRAPP-binding region (TBR) | Provides the physical basis for recruitment of TRAPP/TRAPPIII machinery by TBC1D14 | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Domain organization | ULK1-binding region | The ULK1-interacting region is distinct from the TBR and lies within aa 224–330 | Indicates modular organization: separate surfaces for autophagy kinase interaction and TRAPP binding | (lamb2016tbc1d14regulatesautophagy pages 3-5) |
| Catalytic/mechanistic context | TBC family catalytic mechanism | TBC Rab-GAP proteins generally regulate Rab GTPases via a dual-finger mechanism using conserved catalytic residues in the TBC domain; structurally related TBC proteins require catalytic arginine/Q-finger glutamine residues for GAP activity | Provides the mechanistic baseline for interpreting the conserved cod TBC domain, while not proving TBC1D14 itself is an active Rab GAP toward Rab11 | (chen2017crystalstructureof pages 1-2, popovic2012rabgtpaseactivatingproteins pages 1-2) |
| Primary molecular function | RAB11 binding rather than Rab11 GAP activity | TBC1D14 binds RAB11 and behaves as a RAB11 effector; the literature summarized in the retrieved texts states that TBC1D14 does not appear to act as a GAP for RAB11 | Suggests its primary role is scaffolding/coordination of membrane traffic rather than direct inactivation of Rab11 | (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 14-17) |
| Protein interactors | TRAPP core and associated subunits | TBC1D14 co-immunoprecipitates with TRAPPC4, TRAPPC12, and via TRAPPC3 pulldown is associated with endogenous TBC1D14; BioID and knockdown data indicate TRAPPC8 is the most proximal subunit mediating the interaction | Defines TBC1D14 as a recruiter/partner of a mammalian TRAPPIII-like complex | (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Protein interactors | TRAPPC8 | TRAPPC8 is required for TBC1D14/TBR to bind the core TRAPP complex and is identified as the likely mammalian ortholog of yeast Trs85, the autophagy-specific TRAPPIII subunit | Places TBC1D14 in a Rab1-regulatory, autophagy-relevant tethering pathway | (lamb2016tbc1d14regulatesautophagy pages 7-10, lamb2016tbc1d14regulatesautophagy pages 12-14) |
| Protein interactors | RAB11A/B | TBC1D14-induced tubules are RAB11-positive; prior work cited in the paper established that endogenous RAB11 is required for tubule formation, and RAB11 recruits TBC1D14 to recycling endosome membranes | Supports a model in which TBC1D14 is a RAB11-dependent membrane trafficking factor at recycling endosomes | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 2-3) |
| Protein interactors | RAB1B | Endogenous RAB1B partially colocalizes with TBC1D14 at the Golgi; a subset of TBC1D14-induced tubules simultaneously harbors RAB11A and RAB1B | Supports a Rab conversion/hand-off model linking RAB11-positive recycling endosomes to RAB1-positive early Golgi/ERGIC traffic | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 14-17) |
| Protein interactors | ULK1 | TBC1D14 overexpression was previously linked to a RAB11- and ULK1-positive recycling endosome compartment; ULK1-binding region is distinct from the TRAPP-binding region | Connects TBC1D14 to early autophagy signaling and membrane supply pathways | (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 2-3) |
| Protein interactors | ATG9 / ATG9-positive membranes | ATG9-positive membranes co-isolate with TRAPPC8 and TRAPPC4; TBC1D14/TRAPP activity is required for proper ATG9 localization and cycling | Links TBC1D14 indirectly and functionally to the ATG9 membrane cycle essential for autophagosome biogenesis | (lamb2016tbc1d14regulatesautophagy pages 12-14, lamb2016tbc1d14regulatesautophagy pages 14-17) |
| Subcellular localization | Recycling endosomes | TBC1D14 overexpression generates a tubulated transferrin-positive recycling endosome compartment; endogenous TBC1D14 also localizes to peripheral recycling endosome structures | Indicates action on endocytic recycling membranes, particularly RAB11-positive compartments | (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 12-14) |
| Subcellular localization | Golgi / early Golgi | Endogenous TBC1D14 localizes to the Golgi stack and partially colocalizes with TRAPPC4 and RAB1B; overexpression fragments the GM130-positive cis-Golgi | Positions TBC1D14 at the interface of autophagy-related trafficking and Golgi organization/secretory traffic | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 12-14) |
| Subcellular localization | Transport intermediate between RE and RAB1 compartments | TBC1D14-positive tubules can harbor RAB11A, RAB1B, and TRAPPC4 simultaneously, consistent with a tubulo-vesicular intermediate between recycling endosomes and early Golgi/ERGIC membranes | Suggests TBC1D14 coordinates membrane exchange between endocytic recycling and early secretory systems | (lamb2016tbc1d14regulatesautophagy pages 2-3, lamb2016tbc1d14regulatesautophagy pages 14-17) |
| Primary molecular function | Recruitment of TRAPP/TRAPPIII | TBC1D14 binds TRAPP via its aa 120–223 TBR, and TRAPPC8 mediates this interaction; TBC1D14 overexpression mislocalizes TRAPP to tubulated recycling endosomes | Core scaffolding/adaptor role: recruits tethering/GEF machinery to specific membranes | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Primary molecular function | Promotion of RAB1 activation indirectly through TRAPP | TRAPP is the GEF for RAB1, and TBC1D14 is required but not sufficient for normal RAB1 activation; depletion of TBC1D14 reduces RAB1B binding to the effector golgin-84 | TBC1D14 helps position/enable TRAPPIII-mediated RAB1 activation rather than directly catalyzing RAB1 nucleotide exchange itself | (lamb2016tbc1d14regulatesautophagy pages 10-12, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Primary molecular function | Coordination of membrane traffic for autophagosome formation | Overexpression of TBC1D14 or its TBR inhibits LC3 lipidation, reduces LC3 puncta, and also reduces early autophagy markers WIPI2 and DFCP1 | Establishes TBC1D14 as a regulator of an early step in autophagosome biogenesis | (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Biological process | Autophagy regulation | TBC1D14 is described as a negative regulator of autophagy that controls membrane delivery from RAB11-positive recycling endosomes to forming autophagosomes | Principal characterized biological role in the literature | (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 2-3) |
| Biological process | ATG9 trafficking | TBC1D14 and TRAPPIII regulate ATG9 trafficking independently of ULK1; disruption of TBC1D14/TRAPP/RAB1 function disperses juxtanuclear ATG9 and alters the cycling ATG9 pool | Explains how TBC1D14 influences autophagy mechanistically: by maintaining the membrane itinerary of the only transmembrane core ATG protein | (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 12-14) |
| Biological process | Secretory pathway and Golgi integrity | TBR overexpression impairs constitutive secretion and fragments the Golgi; TRAPPC8 depletion phenocopies Golgi and secretory defects | Indicates TBC1D14 also regulates ER-Golgi/early secretory traffic beyond autophagy | (lamb2016tbc1d14regulatesautophagy pages 5-7, lamb2016tbc1d14regulatesautophagy pages 7-10) |
| Biological process | RE-to-Golgi membrane exchange | The authors propose a constitutive trafficking step from peripheral recycling endosomes to the early Golgi that maintains an ATG9 cycling pool needed for autophagy initiation | Integrates endocytic recycling and early secretory trafficking into a unified TBC1D14 function | (lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 14-17) |
| Cod-specific inference | Most likely conserved functional interpretation for Gadus morhua tbc1d14 | Because cod-specific experiments were not retrieved, the safest annotation is that Atlantic cod Tbc1d14 is likely an intracellular membrane-trafficking regulator associated with the Rab-GAP TBC domain family, probably functioning at recycling endosome/Golgi interfaces and in autophagy-related ATG9 trafficking, but direct substrate specificity and cod-specific localization remain unvalidated | Provides a bounded, evidence-based annotation for A0A8C5FPT8 without overclaiming species-specific function | (lamb2016tbc1d14regulatesautophagy pages 3-5, lamb2016tbc1d14regulatesautophagy pages 1-2, lamb2016tbc1d14regulatesautophagy pages 14-17) |
Table: This table summarizes the best-supported characteristics of TBC1D14 relevant to annotating Atlantic cod tbc1d14, including domains, interactors, localization, functions, and pathways. It is especially useful because direct Gadus morhua literature was not retrieved, so annotation depends on careful transfer from conserved vertebrate evidence.
Based on the comprehensive analysis of conserved TBC1D14 function in mammalian systems and the presence of a conserved Rab-GAP TBC domain in the Atlantic cod protein, the following functional annotation is proposed:
Atlantic cod TBC1D14 (UniProt A0A8C5FPT8) is a membrane trafficking regulator belonging to the TBC domain-containing protein family. The protein likely functions as a RAB11-binding scaffolding protein that coordinates membrane exchange between recycling endosomes and early Golgi/ERGIC compartments. Key predicted functions include:
The protein is predicted to localize to recycling endosomes, Golgi complex, and tubulo-vesicular transport intermediates where it acts as a molecular bridge linking RAB11-positive and RAB1-positive membrane compartments.
Important caveats: (1) No species-specific experimental data for Atlantic cod were identified; (2) specific substrate specificity of the TBC domain in cod is unknown; (3) potential fish-specific functions cannot be predicted from mammalian data; (4) direct GAP activity toward any Rab GTPase has not been demonstrated for TBC1D14 in any species studied to date.
This annotation should be considered a high-confidence inference based on domain conservation and extensive mammalian functional data, but experimental validation in Atlantic cod cells or tissues would be required to confirm these predicted functions.
References
(lamb2016tbc1d14regulatesautophagy pages 1-2): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
(popovic2012rabgtpaseactivatingproteins pages 1-2): Doris Popovic, Masato Akutsu, Ivana Novak, J. Wade Harper, Christian Behrends, and Ivan Dikic. Rab gtpase-activating proteins in autophagy: regulation of endocytic and autophagy pathways by direct binding to human atg8 modifiers. Molecular and Cellular Biology, 32:1733-1744, May 2012. URL: https://doi.org/10.1128/mcb.06717-11, doi:10.1128/mcb.06717-11. This article has 219 citations and is from a domain leading peer-reviewed journal.
(lamb2016tbc1d14regulatesautophagy pages 2-3): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
(chen2017crystalstructureof pages 1-2): Yan‐Na Chen, Xin Gu, X. Edward Zhou, Weidong Wang, Dandan Cheng, Yinghua Ge, Fei Ye, H. Eric Xu, and Zhengbing Lv. Crystal structure of tbc1d15 gtpase‐activating protein (gap) domain and its activity on rab gtpases. Protein Science, 26:834-846, Apr 2017. URL: https://doi.org/10.1002/pro.3132, doi:10.1002/pro.3132. This article has 17 citations and is from a peer-reviewed journal.
(lamb2016tbc1d14regulatesautophagy pages 3-5): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
(lamb2016tbc1d14regulatesautophagy pages 14-17): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
(lamb2016tbc1d14regulatesautophagy pages 7-10): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
(lamb2016tbc1d14regulatesautophagy pages 12-14): Christopher A Lamb, Stefanie Nühlen, Delphine Judith, David Frith, Ambrosius P Snijders, Christian Behrends, and Sharon A Tooze. Tbc1d14 regulates autophagy via the trapp complex and atg9 traffic. The EMBO Journal, 35:281-301, Dec 2016. URL: https://doi.org/10.15252/embj.201592695, doi:10.15252/embj.201592695. This article has 213 citations.
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