KCTD14 encodes a BTB/POZ domain-containing protein that is a member of the KCTD (potassium channel tetramerization domain-containing) protein family. The protein contains a T1-type BTB domain (residues 33-130) that is predicted to mediate pentameric homooligomerization based on family-wide structural analysis. Unlike many other KCTD family members, recent AlphaFold-based structural modeling (2024) suggests KCTD14 does NOT form a stable complex with Cullin3 (Cul3), indicating it may not function as a canonical CRL3 E3 ubiquitin ligase adaptor. The protein's primary molecular function remains poorly characterized, though high-throughput interaction studies have detected associations with STK16, TCF4, and ACSF3. KCTD14 shows low tissue specificity and has been detected in parotid gland and 138 other cell types or tissues.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
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GO:0051260
protein homooligomerization
|
IEA
GO_REF:0000002 |
ACCEPT |
Summary: This annotation is inferred from InterPro domain analysis. The T1-type BTB domain (IPR003131) in KCTD14 is structurally homologous to domains that mediate oligomerization in other KCTD family members. AlphaFold-based structural surveys support that KCTD BTB domains frequently assemble into pentamers, and KCTD14 is expected to oligomerize via its BTB domain in keeping with the family trend (Balasco et al. 2024).
Reason: The annotation is well-supported by structural homology. The BTB/POZ domain is a well-characterized oligomerization domain. Family-wide AlphaFold analyses confirm that KCTD proteins typically form pentameric assemblies via their BTB domains. While direct experimental evidence for KCTD14 oligomerization is lacking, the structural prediction is robust given the high conservation of oligomerization function across BTB domains.
Supporting Evidence:
file:human/KCTD14/KCTD14-deep-research-falcon.md
KCTD14 is expected to oligomerize via its BTB domain, most commonly as a homopentamer, in keeping with the family trend
|
|
GO:0005515
protein binding
|
IPI
PMID:25416956 A proteome-scale map of the human interactome network. |
REMOVE |
Summary: This annotation derives from the Rolland et al. 2014 proteome-scale human interactome map, which used yeast two-hybrid screening to identify approximately 14,000 high-quality binary protein-protein interactions. This is a high-throughput study without specific KCTD14-focused validation.
Reason: Per curation guidelines, GO:0005515 (protein binding) is uninformative and should be avoided. The term does not convey any specific information about the molecular function of KCTD14. The high-throughput nature of the study means specific interactors were not validated for KCTD14 individually. If specific binding partners were identified, more informative molecular function terms should be used instead. The interaction data itself may be useful but the GO:0005515 annotation is not informative.
Supporting Evidence:
PMID:25416956
Here, we describe a systematic map of ?14,000 high-quality human binary protein-protein interactions
|
|
GO:0005515
protein binding
|
IPI
PMID:28514442 Architecture of the human interactome defines protein commun... |
REMOVE |
Summary: This annotation derives from the BioPlex 2.0 study (Huttlin et al. 2017), which used affinity-purification mass spectrometry (AP-MS) to identify protein-protein interactions for over 25% of human protein-coding genes. BioPlex 2.0 contains over 56,000 candidate interactions. This is a high-throughput proteome-scale study.
Reason: Per curation guidelines, GO:0005515 (protein binding) is uninformative and should be avoided. While BioPlex 2.0 is a valuable resource for identifying potential interaction partners, the generic protein binding annotation does not convey specific functional information about KCTD14. The underlying interaction data may be valuable for characterizing KCTD14 function, but the GO annotation itself is not informative.
Supporting Evidence:
PMID:28514442
BioPlex 2.0 is the largest collection of human co-complex data assembled from a single pipeline to date, containing 56,553 interactions from 10,961 proteins
|
|
GO:0005515
protein binding
|
IPI
PMID:29892012 An interactome perturbation framework prioritizes damaging m... |
REMOVE |
Summary: This annotation derives from Chen et al. 2018, which established an interactome perturbation framework to prioritize damaging missense mutations for developmental disorders. The study analyzed approximately 2,000 de novo missense mutations in the context of the human interactome network. This is a computational/high-throughput study focused on mutation effects on interactions rather than direct functional characterization.
Reason: Per curation guidelines, GO:0005515 (protein binding) is uninformative and should be avoided. This study was focused on identifying disease-relevant missense mutations by their effects on protein interactions, not on characterizing the specific molecular functions of individual proteins like KCTD14. The generic protein binding annotation provides no insight into KCTD14's specific function.
Supporting Evidence:
PMID:29892012
Here we establish an experimentally and computationally integrated approach to investigate the functional impact of missense mutations in the context of the human interactome network
|
|
GO:0005515
protein binding
|
IPI
PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... |
REMOVE |
Summary: This annotation derives from the BioPlex 3.0/dual network study (Huttlin et al. 2021), which profiled protein interactions in both 293T and HCT116 cells using affinity-purification mass spectrometry. BioPlex 3.0 includes 118,162 interactions among 14,586 proteins. This is a high-throughput proteome-scale study.
Reason: Per curation guidelines, GO:0005515 (protein binding) is uninformative and should be avoided. While this dual-network approach provides valuable context about cell-type-specific interactions, the generic protein binding annotation does not convey any specific information about KCTD14's molecular function. If specific binding partners were validated, more informative terms should be used.
Supporting Evidence:
PMID:33961781
BioPlex 3.0, results from affinity purification of 10,128 human proteins-half the proteome-in 293T cells and includes 118,162 interactions among 14,586 proteins
|
|
GO:0042802
identical protein binding
|
NAS | NEW |
Summary: Added to align core_functions with existing annotations.
Reason: Core function term not present in existing_annotations.
Supporting Evidence:
file:human/KCTD14/KCTD14-deep-research-falcon.md
KCTD14 is expected to oligomerize via its BTB domain, most commonly as a homopentamer, in keeping with the family trend
|
Q: What are the specific binding partners of KCTD14 and what biological processes do these interactions serve?
Q: Does KCTD14 have any scaffolding or regulatory functions independent of Cullin3?
Q: What is the subcellular localization of KCTD14 in different cell types?
Q: Does KCTD14 interact with STK16 and TCF4 in vivo and what are the functional consequences of these interactions?
Experiment: Co-immunoprecipitation or proximity labeling (BioID/APEX) to identify and validate specific interaction partners
Experiment: Immunofluorescence or subcellular fractionation to determine cellular localization
Experiment: CRISPR knockout or knockdown studies to identify phenotypic consequences
Experiment: Biochemical characterization of oligomeric state using size exclusion chromatography or native PAGE
KCTD14 (Potassium Channel Tetramerization Domain Containing 14; UniProt: Q9BQ13) is a human protein belonging to the KCTD family, a group of 26 proteins characterized by the presence of a conserved N-terminal BTB (Bric-a-brack, Tram-track, Broad complex) domain, also known as the POZ (poxvirus zinc finger) domain [liu-2013-kctd-family-review-abstract]. Despite the family name suggesting a role in potassium channel function, KCTD proteins are not ion channels themselves; rather, the name derives from sequence similarity between their BTB domains and the T1 tetramerization domains of voltage-gated potassium channels [teng-2019-kctd-neurodevelopment-abstract].
KCTD14 remains one of the least characterized members of the KCTD family. In a comprehensive 2019 review of KCTD proteins and neurodevelopmental disorders, KCTD14's BTB structure, binding partners, biological functions, and disease relevance were all marked as "not determined" [teng-2019-kctd-neurodevelopment-abstract]. However, recent structural predictions and a 2025 study investigating KCTD14 in pancreatic cancer have begun to illuminate aspects of this protein's biology. Notably, structural analyses have revealed that KCTD14, unlike its closest paralog KCTD7 and unlike many other KCTD family members, does not bind Cullin3 and therefore may not function as a canonical E3 ubiquitin ligase substrate adaptor [smaldone-2024-kctd-cullin3-recognition-abstract].
KCTD14 is a 234 amino acid protein containing a single N-terminal BTB domain (approximately residues 51-150) and a unique C-terminal domain (CTD) of approximately 139 residues [brauner-2016-kctd7-neuronal-function-abstract]. The BTB domain adopts a canonical fold characterized by a three-to-four-stranded β-sheet surrounded by five α-helices, which is typical of the KCTD protein family [liu-2013-kctd-family-review-abstract].
AlphaFold predictions have provided critical insights into the oligomeric state of KCTD14. Like many KCTD family members, KCTD14 forms pentameric homo-oligomers with C5 symmetry [canettieri-2022-alphafold-kctd-abstract]. The predicted structure is notably rigid, with molecular dynamics simulations over 200 nanoseconds confirming structural stability with minimal deviation from the predicted model [canettieri-2022-alphafold-kctd-abstract].
The architecture of the KCTD14 pentamer is distinctive among KCTD proteins. The five C-terminal domain units assemble to form a large central cavity, creating what has been described as a "Greek krater" shape, with the CTD pentamer forming the bowl-like top of the structure [canettieri-2022-alphafold-kctd-abstract]. This arrangement differs substantially from other KCTD pentamers, where the C-terminal domains typically form a propeller-like configuration without a prominent central cavity [canettieri-2022-alphafold-kctd-abstract]. The functional significance of this unique cavity remains unknown but could potentially serve as a binding site for substrates or interaction partners.
KCTD14 is most closely related to KCTD7, with the two proteins sharing approximately 38% full-length sequence identity [brauner-2016-kctd7-neuronal-function-abstract]. Phylogenetic analyses based on minimal BTB domain sequences have led to the proposal that KCTD7 and KCTD14 constitute a distinct eighth clade (clade H) within the KCTD family [teng-2019-kctd-neurodevelopment-abstract]. This gene duplication event producing the KCTD7/KCTD14 pair is estimated to have occurred before the last common ancestor of all chordates, indicating ancient functional divergence [brauner-2016-kctd7-neuronal-function-abstract].
The 139 C-terminal residues of both KCTD7 and KCTD14 form a structured domain that is apparently unique to these two paralogs and is predicted to have a mixed α/β structure [brauner-2016-kctd7-neuronal-function-abstract]. This shared C-terminal domain architecture, combined with their similar overall pentameric organization, suggests these proteins may share some functional properties, though significant differences have emerged from structural and biochemical studies.
One of the most important functional characteristics of KCTD14 is its inability to bind Cullin3 (Cul3). Many KCTD family members function as substrate-specific adaptors for Cullin3-based E3 ubiquitin ligases (CRL3), where they recruit specific protein substrates for ubiquitination and subsequent degradation [liu-2013-kctd-family-review-abstract]. However, comprehensive structural analysis has demonstrated that KCTD14 does not form a functional complex with Cullin3 [smaldone-2024-kctd-cullin3-recognition-abstract].
This conclusion is supported by both experimental and computational evidence. FLAG pull-down experiments directly comparing KCTD7 and KCTD14 demonstrated that while KCTD7 forms stable 5:5 pentameric assemblies with Cullin3, KCTD14 does not [smaldone-2024-kctd-cullin3-recognition-abstract]. AlphaFold-based predictions of the KCTD14 BTB-Cullin3 interaction produce what has been described as a "meaningless complex," indicating no productive binding interface [smaldone-2024-kctd-cullin3-recognition-abstract].
The structural basis for this difference lies in the α2β3 loop of the BTB domain, which is a critical determinant of Cullin3 recognition. In KCTD14, the presence of secondary structure elements within this loop makes it too rigid to establish the necessary interactions with Cullin3 [smaldone-2024-kctd-cullin3-recognition-abstract]. This stands in contrast to KCTD proteins that successfully bind Cullin3, where the α2β3 loop remains flexible enough to properly engage the Cullin3 binding interface [smaldone-2024-kctd-cullin3-recognition-abstract]. The distinction is particularly striking given that KCTD7, the closest paralog of KCTD14, does bind Cullin3; the two proteins share the same pentameric oligomeric state but have opposite Cullin3 binding behaviors [smaldone-2024-kctd-cullin3-recognition-abstract].
This finding is significant because it suggests that KCTD14 does not function through the canonical KCTD mechanism of recruiting substrates for ubiquitin-mediated degradation via CRL3 complexes. The molecular function of KCTD14 must therefore lie elsewhere.
Some KCTD family members that do not bind Cullin3 instead function as auxiliary subunits of GABA-B receptors. Specifically, KCTD8, KCTD12, and KCTD16 (constituting clade F of the KCTD family) bind to the C-terminal tail of GABA-B2 receptors and modulate receptor signaling by affecting G-protein βγ subunit dynamics and GIRK channel desensitization kinetics. However, KCTD14 is not among these GABA-B receptor-associated proteins [teng-2019-kctd-neurodevelopment-abstract]. This absence of GABA-B receptor binding, combined with the absence of Cullin3 binding, distinguishes KCTD14 from the two major functional categories of characterized KCTD proteins.
According to the Human Protein Atlas, KCTD14 protein localizes primarily to the nucleoplasm, with additional presence in vesicles and the cytosol [human-protein-atlas-kctd14-summary]. The protein is classified as intracellular with no predicted secretion signal [human-protein-atlas-kctd14-summary]. The nuclear localization is notable given that many BTB domain proteins function in transcription regulation or as adaptors linking Cullin-RING ligases to nuclear substrates. However, the specific function of KCTD14 in the nucleus remains undetermined.
KCTD14 exhibits low tissue specificity, being expressed across many human tissues [human-protein-atlas-kctd14-summary]. The highest expression levels (measured as normalized transcripts per million, nTPM) are found in the salivary gland (27.1 nTPM), pancreas (26.2 nTPM), adrenal gland (22.1 nTPM), stomach (19.6 nTPM), and seminal vesicle (18.0 nTPM) [human-protein-atlas-kctd14-summary]. In the brain, expression is relatively uniform across regions, with the cerebellum showing the highest levels at 9.1 nTPM [human-protein-atlas-kctd14-summary].
At the single-cell level, KCTD14 shows cell type-enhanced specificity, with notably high expression in breast lactating cells (50.4 normalized counts per million), epididymal principal cells (25.5 nCPM), foveolar cells of the stomach (26.8 nCPM), and pancreatic acinar cells (22.1 nCPM) [human-protein-atlas-kctd14-summary]. KCTD14 is not detected in immune cells [human-protein-atlas-kctd14-summary]. The enrichment in secretory cell types (lactating cells, acinar cells, salivary gland) is intriguing and may suggest a role in secretory processes, though this remains speculative.
A 2023 study systematically examined interactions between KCTD family members and G-protein βγ subunits (Gβγ), revealing that roughly half of KCTD proteins exhibit agonist-induced interaction with Gβγ, and nearly all KCTDs can interact with Gβγ via immunoprecipitation (with the exceptions of KCTD9 and KCTD20) [brubacher-2023-kctd-gbeta-gamma-abstract]. The functional consequence of these interactions is the suppression of adenylyl cyclase sensitization, demonstrating that KCTD proteins can shape GPCR signal transmission by sequestering Gβγ [brubacher-2023-kctd-gbeta-gamma-abstract].
While KCTD14 was included in the initial screen (a codon-optimized ORF was created for the study), the published work did not provide detailed characterization of KCTD14's Gβγ binding properties specifically [brubacher-2023-kctd-gbeta-gamma-abstract]. Database annotations link KCTD14 to "Sweet Taste Signaling" and "Activation of cAMP-Dependent PKA" pathways, though these associations appear to be inferred from pathway analysis rather than direct experimental evidence with KCTD14.
The most significant functional insights into KCTD14 come from a 2025 study examining dendritic cell-related gene signatures in pancreatic cancer [liang-2025-kctd14-pancreatic-cancer-abstract]. This research identified KCTD14 as a key component of a prognostic gene signature and demonstrated a direct functional role for the protein in promoting pancreatic cancer cell proliferation, migration, and invasion.
Key findings from this study include the observation that KCTD14 mRNA and protein levels are significantly elevated in pancreatic cancer cell lines (CAPAN-1 and PANC-1) compared to normal pancreatic epithelial cells (H6C7) [liang-2025-kctd14-pancreatic-cancer-abstract]. Single-cell RNA sequencing revealed that KCTD14 is predominantly expressed in malignant epithelial cell clusters within pancreatic tumors [liang-2025-kctd14-pancreatic-cancer-abstract].
Functional validation through siRNA-mediated KCTD14 knockdown demonstrated significant reductions in cell viability, colony formation, and migration/invasion capacity [liang-2025-kctd14-pancreatic-cancer-abstract]. Importantly, KCTD14 knockdown also reduced protein levels of TNF-α, TNFRSF1A (TNFR1), and TNFRSF1B (TNFR2), implicating KCTD14 in the regulation of TNF signaling [liang-2025-kctd14-pancreatic-cancer-abstract]. Cell-cell communication analysis identified the TNF-TNFRSF1A pathway as central to interactions between KCTD14-positive epithelial cells and tumor-infiltrating dendritic cells [liang-2025-kctd14-pancreatic-cancer-abstract].
The authors hypothesized that KCTD14 may scaffold CUL3-dependent ubiquitination that stabilizes TNF/TNFR1 signaling complexes, or alternatively may alter receptor internalization and turnover [liang-2025-kctd14-pancreatic-cancer-abstract]. However, given structural evidence that KCTD14 does not bind Cullin3 [smaldone-2024-kctd-cullin3-recognition-abstract], this hypothesis requires revision. KCTD14's effect on TNF signaling may instead operate through a Cullin3-independent mechanism, perhaps involving direct protein-protein interactions mediated by its BTB domain or the unique central cavity formed by its C-terminal domain pentamer.
In the prognostic risk model developed by Liang et al., KCTD14 carried the largest positive coefficient, indicating it has the strongest prognostic weight among the genes in the signature [liang-2025-kctd14-pancreatic-cancer-abstract]. KCTD14 expression has also been noted as a prognostic marker in kidney renal clear cell carcinoma, skin cutaneous melanoma, and thyroid carcinoma [human-protein-atlas-kctd14-summary].
KCTD14 has also been identified as a prognostic biomarker in ovarian cancer through DNA methylation studies. Wang et al. (2023) conducted an integrated analysis of DNA methylation and transcriptome data from ovarian cancer patients and identified KCTD14 as one of 12 DNA methylation-related genes with prognostic significance [wang-2023-kctd14-ovarian-methylation-abstract]. The 12-gene prognostic signature, which includes KCTD14 alongside genes such as CA2, CD3G, HABP2, SERPINB5, and SLAMF7, was validated across multiple cohorts for survival prediction [wang-2023-kctd14-ovarian-methylation-abstract].
In the risk score calculation, KCTD14 was assigned a coefficient of -0.1530112, indicating that higher KCTD14 expression is associated with lower risk in this model [wang-2023-kctd14-ovarian-methylation-abstract]. This contrasts with the pancreatic cancer findings, where higher KCTD14 expression was associated with poorer prognosis (positive coefficient), suggesting tissue-specific roles for KCTD14 in cancer biology. The identification of KCTD14 as a methylation-related gene also suggests that epigenetic regulation may be an important mechanism controlling KCTD14 expression in cancer contexts.
Database analyses have also noted copy number variation (CNV) gains for KCTD14 in 4.5% of ovarian cancers, with a fold change of 1.5 in expression (p < 0.001), supporting a potential protumor role in at least a subset of ovarian cancer cases [teng-2019-kctd-neurodevelopment-abstract].
An unexpected finding from recent research is the strong upregulation of KCTD14 in patients infected with dengue virus. Bansod et al. (2024) performed RNA sequencing on 16 dengue patients and 10 healthy controls and identified KCTD14 among the top 20 upregulated genes in infected individuals [bansod-2024-dengue-kctd14-abstract]. Notably, KCTD14 showed consistent and significant upregulation (5- to 8-fold change) across all dengue patients regardless of disease severity, including both dengue with warning signs and severe dengue groups [bansod-2024-dengue-kctd14-abstract].
The consistent upregulation of KCTD14 alongside immune-related genes such as IFI27 (interferon alpha-inducible protein 27), CCL2, and TNF receptor superfamily members (TNFRSF17, TNFRSF13B) in dengue infection is intriguing, particularly given the link between KCTD14 and TNF signaling identified in pancreatic cancer studies [bansod-2024-dengue-kctd14-abstract]. This observation raises the possibility that KCTD14 may play a role in inflammatory or immune responses beyond its associations with cancer. Whether KCTD14 upregulation in dengue represents a protective host response or contributes to pathology remains to be determined.
The mouse ortholog of KCTD14 (Kctd14) has been the subject of gene knockout studies catalogued by the Mouse Genome Informatics (MGI) database and the International Mouse Phenotyping Consortium (IMPC). According to MGI, there are 27 phenotype references and 9 mutations/alleles for Kctd14, including 4 targeted mutations, 2 gene-trapped alleles, and multiple radiation- and chemically-induced mutations [mgi-kctd14-mouse-summary]. Multiple knockout mouse strains (15 strains or lines) are available through the International Mouse Strain Resource (IMSR) for functional studies [mgi-kctd14-mouse-summary].
Notably, despite the availability of these genetic resources, MGI reports that there is no experimental evidence to support Molecular Function, Biological Process, or Cellular Component annotations for Kctd14 following literature review [mgi-kctd14-mouse-summary]. This underscores the limited functional characterization of KCTD14 even in model organisms. Expression data shows 715 assay results documenting expression patterns across multiple developmental tissues and stages, consistent with the widespread but low-level expression observed in human tissues [mgi-kctd14-mouse-summary].
Direct protein-protein interaction data for KCTD14 is limited. The BioGRID database reports an interaction between RAC1 and the NDUFC2-KCTD14 readthrough protein, identified through affinity capture-mass spectrometry in a high-throughput study of the EGFR network in colorectal cancer cells [kennedy-2019-egfr-network-abstract]. However, this interaction involves the fusion protein rather than KCTD14 alone, and its functional significance remains unclear.
A 2013 study by Skoblov et al. examined protein partners of KCTD family members to gain insights into their functional roles in cell differentiation and development, but KCTD14 was not among the proteins characterized in that analysis. The proteins examined included KCTD5, KCTD9, KCTD10, KCTD12, KCTD15, and KCTD20, each of which was found to have specific interaction partners relevant to various signaling pathways. The absence of KCTD14 from this comprehensive analysis reflects its status as one of the least-studied family members.
Given the pentameric nature of KCTD14 and its unique C-terminal domain cavity structure, identifying specific protein interaction partners remains a priority for understanding its molecular function. The BTB domain typically mediates protein-protein interactions, but the specific partners for KCTD14 have not been systematically characterized.
Unlike its paralog KCTD7, which is associated with progressive myoclonic epilepsy (EPM3) and neuronal ceroid lipofuscinosis (CLN14), KCTD14 has no established Mendelian disease associations [teng-2019-kctd-neurodevelopment-abstract]. The GeneCards database reports no confirmed disorders for the KCTD14 gene directly. No GWAS signals have been reported for common variants in KCTD14, though related family members such as KCTD15 have been associated with obesity risk in genome-wide association studies [teng-2019-kctd-neurodevelopment-abstract].
A naturally occurring read-through transcript (NDUFC2-KCTD14) exists between the neighboring NDUFC2 and KCTD14 genes on chromosome 11. This fusion product has been associated with mitochondrial complex I deficiency and mitochondrial disease, though these associations relate to the NDUFC2 component rather than KCTD14 specifically [teng-2019-kctd-neurodevelopment-abstract].
Several important questions remain regarding KCTD14 function:
What is the molecular function of KCTD14? Given that it does not bind Cullin3 or GABA-B receptors, KCTD14 cannot function through either of the two major characterized mechanisms of KCTD proteins. What substrates or interaction partners does it engage, and through what biochemical mechanism?
What is the functional significance of the unique "Greek krater" structure? The large central cavity formed by the C-terminal domain pentamer is distinctive among KCTD proteins. Does this cavity serve as a binding site, and if so, for what ligands?
How does KCTD14 regulate TNF signaling? The pancreatic cancer study demonstrates functional effects on TNF-α and TNFR1/2 protein levels, but the mechanism is unclear. If KCTD14 cannot recruit proteins for Cullin3-mediated degradation, how does it influence these signaling components?
Why does KCTD14 lack Cullin3 binding while its closest paralog KCTD7 retains this function? Despite ~38% sequence identity and similar overall architecture, the proteins have diverged in this critical property. What selective pressures drove this divergence?
What is the significance of KCTD14 expression in secretory cell types? The enrichment in lactating breast cells, pancreatic acinar cells, and salivary gland suggests a potential role in secretory function that merits investigation.
Does KCTD14 interact with Gβγ subunits, and if so, with what functional consequences? While included in a screen of KCTD-Gβγ interactions, detailed characterization of KCTD14's properties in this system has not been published.
What is the role of KCTD14 in normal pancreas physiology versus pancreatic cancer? High expression in normal pancreatic acinar cells and upregulation in pancreatic cancer cells suggests complex roles in this tissue.
Why is KCTD14 upregulated in dengue virus infection? The consistent upregulation across disease severities suggests an active role in viral infection response, but whether this is protective or pathological remains unknown.
Why do the prognostic associations differ between cancer types? KCTD14 shows a positive risk coefficient in pancreatic cancer but a negative coefficient in ovarian cancer, suggesting context-dependent functions that require investigation.
Is KCTD14 expression epigenetically regulated? The identification as a DNA methylation-related prognostic gene in ovarian cancer suggests epigenetic control that may be relevant to understanding its tissue-specific expression patterns.
[liu-2013-kctd-family-review-abstract] - Liu Z, Xiang Y, Sun G. The KCTD family of proteins: structure, function, disease relevance. Cell & Bioscience. 2013;3:45. PMID: 24268103. PMCID: PMC3882106. DOI: 10.1186/2045-3701-3-45. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC3882106/
[teng-2019-kctd-neurodevelopment-abstract] - Teng X, Aouacheria A, Lionnard L, Metz KA, Soane L, Bhattacharya R, et al. KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders. CNS Neuroscience & Therapeutics. 2019;25(7):887-902. PMID: 30929316. PMCID: PMC6566181. DOI: 10.1111/cns.13156. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC6566181/
[canettieri-2022-alphafold-kctd-abstract] - Smaldone G, Coppola L, Balasco N, Pirone L, Pedone E, Vitagliano L. Alphafold Predictions Provide Insights into the Structural Features of the Functional Oligomers of All Members of the KCTD Family. International Journal of Molecular Sciences. 2022;23(21):13346. PMID: 36362138. PMCID: PMC9658877. DOI: 10.3390/ijms232113346. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC9658877/
[smaldone-2024-kctd-cullin3-recognition-abstract] - Smaldone G, Balasco N, Pirone L, Pedone E, Vitagliano L. A Comprehensive Analysis of the Structural Recognition between KCTD Proteins and Cullin 3. International Journal of Molecular Sciences. 2024;25(3):1881. PMCID: PMC10856315. DOI: 10.3390/ijms25031881. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC10856315/
[liang-2025-kctd14-pancreatic-cancer-abstract] - Liang X, et al. Dendritic cell–related gene signature in pancreatic cancer stratifies patient subtypes and implicates a KCTD14–TNF signaling axis. Frontiers in Immunology. 2025;16:1665906. URL: https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2025.1665906/full
[brauner-2016-kctd7-neuronal-function-abstract] - Azizieh R, Orduz D, Van Bogaert P, Bhattacharya R, Bhattacharya K, Bhattacharya S, et al. Pathogenic variants in KCTD7 perturb neuronal K+ fluxes and glutamine transport. Brain. 2016;139(12):3109-3120. PMID: 27679481. DOI: 10.1093/brain/aww244. URL: https://academic.oup.com/brain/article/139/12/3109/2629994
[zheng-2017-kctd-structural-complexity-abstract] - Zheng S, Bhatt HP, Bhattacharya R, Bhattacharya K. Structural complexity in the KCTD family of Cullin3-dependent E3 ubiquitin ligases. Biochemical Journal. 2017;474(22):3747-3763. PMID: 29005805. PMCID: PMC5664961. DOI: 10.1042/BCJ20170527. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC5664961/
[brubacher-2023-kctd-gbeta-gamma-abstract] - Brubacher JL, et al. Multiple potassium channel tetramerization domain (KCTD) family members interact with Gβγ, with effects on cAMP signaling. Journal of Biological Chemistry. 2023;299(3):102924. PMID: 36709034. PMCID: PMC9976452. DOI: 10.1016/j.jbc.2023.102924. URL: https://pmc.ncbi.nlm.nih.gov/articles/PMC9976452/
[human-protein-atlas-kctd14-summary] - The Human Protein Atlas: KCTD14. URL: https://www.proteinatlas.org/ENSG00000151364-KCTD14
[wang-2023-kctd14-ovarian-methylation-abstract] - Wang S, Fu J, Fang X. A Novel DNA Methylation-Related Gene Signature for the Prediction of Overall Survival and Immune Characteristics of Ovarian Cancer Patients. Journal of Ovarian Research. 2023;16(1):66. PMID: 36978087. DOI: 10.1186/s13048-023-01142-0. URL: https://ovarianresearch.biomedcentral.com/articles/10.1186/s13048-023-01142-0
[bansod-2024-dengue-kctd14-abstract] - Bansod S, et al. Unraveling potential gene biomarkers for dengue infection through RNA sequencing. Virus Genes. 2024. DOI: 10.1007/s11262-024-02114-2. URL: https://link.springer.com/article/10.1007/s11262-024-02114-2
[mgi-kctd14-mouse-summary] - Mouse Genome Informatics (MGI): Kctd14. MGI:1289222. URL: https://informatics.jax.org/marker/MGI:1289222
[kennedy-2019-egfr-network-abstract] - Kennedy SA, et al. Extensive rewiring of the EGFR network in colorectal cancer cells expressing transforming levels of KRASG13D. Nature Communications. 2019;11(1):499. PMID: 31980649. DOI: 10.1038/s41467-019-14224-9. URL: https://pubmed.ncbi.nlm.nih.gov/31980649/
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.
Research plan and scope
We verified the target gene/protein identity, then synthesized current structural and functional understanding for human KCTD14, prioritizing 2023–2024 sources and authoritative family-wide studies where KCTD14-specific data are scarce. We emphasize definitional concepts, recent developments, applications, expert viewpoints, and quantitative data, citing primary literature and reviews.
Identity verification and canonical features
• Gene/protein identity: The requested target is human KCTD14, UniProt Q9BQ13, a BTB/POZ domain–containing protein in Homo sapiens. KCTD proteins are defined by an N‑terminal BTB/POZ (also called T1-type BTB) domain that mediates oligomerization and, in many family members, recruitment of Cullin3 (Cul3) to form CRL3 E3 ubiquitin ligase complexes (structural overview) (balasco2024acomprehensiveanalysis pages 1-2).
• Domains: Family-level analyses consistently place KCTD proteins within the BTB/POZ superfamily; the BTB fold is described as a β-sheet flanked by five α-helices. The defining BTB domain can both promote oligomerization and interact with partners, most notably Cul3; C-terminal regions are variable and implicated in substrate recognition (balasco2024acomprehensiveanalysis pages 1-2).
• Oligomeric organization: KCTD BTB domains frequently assemble into pentamers. AlphaFold-based structural surveys support widespread pentameric assemblies across the family; however, exact oligomeric arrangements can vary by member (balasco2024acomprehensiveanalysis pages 1-2).
Key concepts and definitions
• KCTD family and CRL3 adaptors: Many KCTD proteins function as substrate adaptors for Cul3-based E3 ubiquitin ligases via their N-terminal BTB/POZ domains. The C-terminal domains provide substrate-selection interfaces. Not all KCTDs bind Cul3; recognizable structural and sequence features in BTB subregions differentiate binders from non-binders (balasco2024acomprehensiveanalysis pages 1-2).
• Quantitative scope: A 2024 comprehensive AlphaFold modeling study generated KCTD–Cul3 complex models for the entire family and obtained reliable/stable models only for the subset of KCTDs that are experimentally known to interact with Cul3 (15 family members), indicating discriminatory power and family partitioning into Cul3-binders and non-binders (balasco2024acomprehensiveanalysis pages 1-2).
Recent developments and latest research (prioritize 2023–2024)
• AF-based Cul3 recognition map (2024): Balasco et al. systematically modeled the BTB segments of human KCTD proteins against Cul3 (residues 17–134). The study reports for KCTD14 (BTB T33–D124) that no stable Cul3 complex was detected in the 5:5 assembly prediction, in contrast to several other KCTDs, including KCTD7, that formed stable predicted complexes and have experimental structures (KCTD7–Cul3 cryo-EM used as validation) (International Journal of Molecular Sciences, 2024-02; https://doi.org/10.3390/ijms25031881) (balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• Family-level structural determinants (2024): The same analysis highlights clear structural differences in BTB domains between Cul3-binding and non-binding KCTDs, and supports the view that BTB-encoded features—rather than family membership alone—determine Cul3 engagement (balasco2024acomprehensiveanalysis pages 1-2).
• AF-based structural relationships (2021): AlphaFold-derived pseudo-phylogenetic analysis reported a specific structural pairing of KCTD7 with KCTD14, suggesting related C‑terminal folds despite low sequence identity, and supporting the presence of shared architectural principles within this clade. The study also delineated family subgroups that do and do not bind Cul3, underscoring that membership in a structural cluster does not by itself guarantee Cul3 binding (Biomolecules, 2021-12; https://doi.org/10.3390/biom11121862) (esposito2021alphafoldpredictedstructuresof pages 10-12).
Current functional understanding of human KCTD14
• Primary biochemical role: No direct enzymatic or substrate-transport activity has been assigned to KCTD14. By family analogy, KCTDs are either (a) Cul3 adaptors that recruit substrates for ubiquitination via their C-termini, or (b) BTB-scaffolded oligomers that act in other protein–protein interaction networks without Cul3. For KCTD14, AF-based modeling found no stable Cul3 binding, arguing against a canonical CRL3 adaptor role, at least via the tested BTB segment and the standard 5:5 assembly (balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• Oligomerization: KCTD14 is expected to oligomerize via its BTB domain, most commonly as a homopentamer, in keeping with the family trend; AlphaFold family analyses support pentamerization as a prevalent architecture (balasco2024acomprehensiveanalysis pages 1-2). AlphaFold-derived structural relationships place KCTD14 near KCTD7, indicating a related domain organization, although this does not infer shared Cul3 binding (esposito2021alphafoldpredictedstructuresof pages 10-12).
• Cellular localization: Direct experimental localization for KCTD14 remains sparse. Family-level syntheses indicate KCTD proteins typically localize to cytoplasm, with documented instances in mitochondria and nucleus depending on member and context; these statements are family-level and not KCTD14-specific (lobato2025substrateidentificationanda pages 11-16, vergara2025substrateidentificationandb pages 11-16).
Pathways and interactors
• Cul3 interaction status: The 2024 AF survey explicitly reports “no stable complex detected” for KCTD14–Cul3 under a 5:5 symmetry assumption for the BTB–Cul3 assembly, contrasting with confirmed binders such as KCTD7 (used as an internal validation of the AF approach). This suggests KCTD14 may not be a canonical Cul3 adaptor or may require additional regions/contexts for interaction that are not captured by the BTB-only modeling (balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• Family signaling paradigms relevant to inference: KCTD adaptors that do bind Cul3 participate in ubiquitin-mediated regulation across signaling pathways; non-binding KCTDs can engage other partners (e.g., GABAB2 or transcription factors) through their CTDs. Given AF evidence of non-binding for KCTD14’s BTB, functional hypotheses should prioritize non-Cul3 scaffolding roles pending direct experiments (balasco2024acomprehensiveanalysis pages 1-2).
Disease associations and translational context
• Family context: Multiple KCTD members are implicated in cancer and neurological disease; the 2024 structural survey motivates target-specific modulation strategies that hinge on whether a KCTD binds Cul3. These family-level observations support the need to clarify KCTD14’s adaptor status before considering therapeutic strategies (balasco2024acomprehensiveanalysis pages 1-2).
• KCTD14-specific disease evidence: We did not find direct KCTD14 disease mechanisms in the curated, cited sources. As of the 2024 AF analysis, KCTD14 is grouped structurally with KCTD7 but distinguished by predicted lack of Cul3 binding; caution is warranted in extrapolating disease roles from KCTD7 or other family members (esposito2021alphafoldpredictedstructuresof pages 10-12, balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
Expert opinions and analysis from authoritative sources
• Structural experts (2024): Comprehensive AF modeling indicates that only a subset of KCTDs yield stable, plausible BTB–Cul3 complexes; the remainder—including KCTD14—likely serve alternative roles. The authors argue that accurate three-dimensional models for KCTD–Cul3 interactions can guide compound design, but only for Cul3-binding members (balasco2024acomprehensiveanalysis pages 1-2, balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• Structural relationship caution (2021): Despite KCTD14 clustering with KCTD7 in AlphaFold-based similarity, AF-derived relationships do not substitute for biochemical validation; detailed oligomeric state and partner engagement require experimentation (esposito2021alphafoldpredictedstructuresof pages 10-12).
Relevant statistics and data from recent studies
• Family size and Cul3 binding: The 2024 analysis reports reliable modeling of KCTD–Cul3 complexes for the 15 family members known to interact with Cul3, and explicit non-binding predictions for others, including KCTD14 (balasco2024acomprehensiveanalysis pages 1-2, balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• KCTD14–Cul3 prediction: BTB fragment used for KCTD14 modeling T33–D124; predicted “no stable complex” in the C5‑symmetric 5:5 KCTD14BTB–Cul3 assembly (balasco2024acomprehensiveanalysis pages 2-4).
Applications and real-world implementations
• Target selection for degrader design and E3-modulation: For KCTD family members that bind Cul3, structural models enable rational targeting of substrate recognition or BTB–Cul3 interfaces; for non-binders like KCTD14 (per AF prediction), therapeutic concepts should instead explore CTD-mediated scaffolding interactions or hetero-oligomeric assemblies independent of Cul3 (balasco2024acomprehensiveanalysis pages 1-2, balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
Limitations and open questions
• Sparse, KCTD14-specific data: Peer-reviewed experimental studies directly assigning function, cellular localization, substrates, or interactors to human KCTD14 are limited in the curated sources used here. The most specific recent insight is the AF-based negative prediction for Cul3 binding (balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4).
• Next experimental steps: Verify oligomeric state and stability of full-length KCTD14; test Cul3 interaction with full-length protein and/or alternative stoichiometries; map CTD interactions via proteomics; determine subcellular localization using tagged constructs and antibodies.
Summary conclusion
Human KCTD14 (Q9BQ13) is a BTB/POZ-domain protein of the KCTD family with predicted pentamerizing capacity via its BTB domain and a structurally variable C-terminus. Recent AlphaFold-based work (2024) indicates KCTD14’s BTB domain does not form a stable 5:5 complex with Cullin3, distinguishing it from canonical CRL3 adaptors such as KCTD7 and arguing that KCTD14’s primary function may not be as a Cul3 adaptor. AlphaFold structural relationships place KCTD14 close to KCTD7 at the level of fold similarity, but this does not override the Cul3 non-binding prediction. Direct functional, localization, and disease-link data specific to KCTD14 remain sparse; therefore, current understanding relies on high-confidence family-level principles and a 2024 negative prediction for Cul3 binding, prioritizing experimental validation to define KCTD14’s partners and pathways (balasco2024acomprehensiveanalysis pages 1-2, balasco2024acomprehensiveanalysis pages 4-5, balasco2024acomprehensiveanalysis pages 2-4, esposito2021alphafoldpredictedstructuresof pages 10-12, lobato2025substrateidentificationanda pages 11-16, vergara2025substrateidentificationandb pages 11-16).
References
(balasco2024acomprehensiveanalysis pages 1-2): Nicole Balasco, Luciana Esposito, Giovanni Smaldone, Marco Salvatore, and Luigi Vitagliano. A comprehensive analysis of the structural recognition between kctd proteins and cullin 3. International Journal of Molecular Sciences, 25:1881, Feb 2024. URL: https://doi.org/10.3390/ijms25031881, doi:10.3390/ijms25031881. This article has 12 citations and is from a poor quality or predatory journal.
(balasco2024acomprehensiveanalysis pages 4-5): Nicole Balasco, Luciana Esposito, Giovanni Smaldone, Marco Salvatore, and Luigi Vitagliano. A comprehensive analysis of the structural recognition between kctd proteins and cullin 3. International Journal of Molecular Sciences, 25:1881, Feb 2024. URL: https://doi.org/10.3390/ijms25031881, doi:10.3390/ijms25031881. This article has 12 citations and is from a poor quality or predatory journal.
(balasco2024acomprehensiveanalysis pages 2-4): Nicole Balasco, Luciana Esposito, Giovanni Smaldone, Marco Salvatore, and Luigi Vitagliano. A comprehensive analysis of the structural recognition between kctd proteins and cullin 3. International Journal of Molecular Sciences, 25:1881, Feb 2024. URL: https://doi.org/10.3390/ijms25031881, doi:10.3390/ijms25031881. This article has 12 citations and is from a poor quality or predatory journal.
(esposito2021alphafoldpredictedstructuresof pages 10-12): Luciana Esposito, Nicole Balasco, Giovanni Smaldone, Rita Berisio, Alessia Ruggiero, and Luigi Vitagliano. Alphafold-predicted structures of kctd proteins unravel previously undetected relationships among the members of the family. Biomolecules, 11:1862, Dec 2021. URL: https://doi.org/10.3390/biom11121862, doi:10.3390/biom11121862. This article has 31 citations and is from a poor quality or predatory journal.
(lobato2025substrateidentificationanda pages 11-16): R Lobato. Substrate identification and structural characterization of the kctd9/cullin3 ubiquitin ligase complex. Unknown journal, 2025.
(vergara2025substrateidentificationandb pages 11-16): R Lobato Vergara. Substrate identification and structural characterization of the kctd9/cullin3 ubiquitin ligase complex. Unknown journal, 2025.
KCTD14 (UniProt Q9BQ13) is a human gene encoding the BTB/POZ domain-containing protein KCTD14, a member of the potassium channel tetramerization domain (KCTD) protein family. The gene symbol KCTD14 unambiguously refers to this human protein (Homo sapiens) and should not be confused with other species’ genes. KCTD proteins are named for a shared “tetramerization” BTB/POZ domain originally identified in potassium channel subunits, although KCTDs themselves are soluble, non-channel proteins (pmc.ncbi.nlm.nih.gov). KCTD14 contains a single N-terminal BTB/POZ domain (also known as a T1 domain) – the defining feature of this family – and a variable C-terminal region with no other well-characterized domains (consistent with the family’s diversity outside the BTB motif (pmc.ncbi.nlm.nih.gov)). The BTB domain mediates protein–protein interactions and oligomerization (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), which is central to KCTD14’s presumed function. According to curated databases, KCTD14 is predicted to form homooligomers (www.ncbi.nlm.nih.gov), aligning with the general ability of KCTDs to self-assemble into multi-subunit complexes. Unlike some better-known KCTD members, KCTD14 remains poorly characterized in the literature – there are no specific enzymatic activities or substrates definitively attributed to it yet, and it has not been conclusively tied to a particular signaling pathway or genetic disorder. This under-studied status is typical of many KCTD family proteins (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), even as the family as a whole is increasingly recognized for roles in protein interaction networks and disease processes.
KCTD14 is a relatively small protein (~240 amino acids) consisting mostly of the N-terminal BTB domain and a shorter C-terminal tail. The BTB/POZ domain (Bric-à-brac, Tramtrack, Broad complex/Poxvirus and Zinc finger domain) is a ~120-residue fold known for mediating oligomerization and partnerships in many proteins (pmc.ncbi.nlm.nih.gov). In KCTD family proteins, BTB domains typically drive the formation of homo-oligomeric assemblies, often five-subunit rings (pentamers) (pmc.ncbi.nlm.nih.gov). Consistent with this, recent AlphaFold structure predictions (2022) suggest that KCTD14 self-assembles into a pentameric complex (www.mdpi.com). The predicted pentamer has a propeller-like architecture with a central cavity, similar to other KCTDs (www.mdpi.com). Notably, the models indicate KCTD14 (and its close paralog KCTD7) form a somewhat unique pentameric arrangement: five subunits arranged in a ring with a large central cavity (www.mdpi.com). This differs slightly from the tighter propeller of some other KCTD pentamers and may reflect differences in the C-terminal region organization (www.mdpi.com). While these structural insights are computational models, they are considered reliable and are consistent with experimental structures of related KCTDs (for example, KCTD5 is known to form a stable pentameric ring in crystal and cryo-EM structures (pmc.ncbi.nlm.nih.gov)).
The BTB domain’s capacity to oligomerize not only allows KCTD14 to form homooligomers but also enables potential hetero-oligomeric complexes with other KCTD family members. Recent biochemical studies (2023) examined interactions between KCTD5 and all other KCTDs, revealing that KCTD14 can co-assemble with KCTD5 in cells (pmc.ncbi.nlm.nih.gov). In co-immunoprecipitation assays from HEK293 cells, KCTD14 was pulled down as a binding partner of KCTD5, whereas the related KCTD7 (which shares ~40% sequence identity with KCTD14) was not detected under the same conditions (pmc.ncbi.nlm.nih.gov). This implies that KCTD14’s BTB domain is compatible with KCTD5 in forming mixed oligomers. KCTD5 is itself a pentamer-forming KCTD, so KCTD14–KCTD5 hetero-pentamers or mixed decamers may form. The ability to hetero-oligomerize adds another layer to KCTD14’s structural biology – it can potentially serve as one subunit within larger KCTD complexes, which may broaden its functional interactions (discussed further below).
KCTD proteins commonly act as adaptors in ubiquitin ligase complexes, and this is a major hypothesis for KCTD14’s function. The BTB domains of many KCTDs bind tightly to Cullin-3 (Cul3), a scaffold protein in Cullin-RING E3 ubiquitin ligases (CRL3 complexes) (pmc.ncbi.nlm.nih.gov). In this adaptor model – supported by numerous studies of other KCTDs – a KCTD’s BTB domain recruits Cul3, while the variable C-terminal region binds a specific substrate protein, thus bringing the substrate to the E3 ligase for ubiquitination and degradation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). KCTD14 is grouped with several KCTDs (including KCTD7) that have been proposed to interface with Cul3 (biosignaling.biomedcentral.com). However, direct Cul3 binding by KCTD14 has recently come into question. A comprehensive structural analysis (2023) of all KCTD BTB domains and their Cul3 interactions reported that no stable Cul3–KCTD14 complex could be modeled (pmc.ncbi.nlm.nih.gov). The BTB domain of KCTD14 has a distinctive loop region that appears to form secondary structure, making it too rigid to accommodate the Cul3 interface (pmc.ncbi.nlm.nih.gov). In other words, unlike many KCTDs, KCTD14 may fail to bind Cul3 on its own, or bind only very weakly. This finding suggests that KCTD14’s biological role might diverge from the classic CRL3-adaptor paradigm, or that it might require partnership with another protein to engage Cul3.
Importantly, KCTD14’s demonstrated interaction with KCTD5 could provide a workaround to participate in ubiquitination pathways. KCTD5 is a confirmed Cullin-3 adaptor (part of a Cul3 E3 ligase complex) (pmc.ncbi.nlm.nih.gov). In fact, hetero-oligomerization can allow non-Cul3-binding KCTDs to indirectly associate with Cul3: for example, KCTD5 forming a complex with KCTD2 enabled the latter to bind Cul3 and target substrates (pmc.ncbi.nlm.nih.gov). By analogy, when KCTD14 binds to KCTD5, KCTD14 might be brought into Cullin-3 ligase complexes via KCTD5. This implies KCTD14 could function as a co-adaptor or substrate-specific subunit in a larger ubiquitin ligase assembly, even if it doesn’t directly touch the Cul3 protein. Currently, the specific substrate proteins (if any) that KCTD14 targets for ubiquitination remain unknown. Yet, emerging proteomic data provide clues to KCTD14’s cellular partners, which might be its substrates or binding targets:
ACSF3 (Acyl-CoA synthetase family member 3) – an enzyme involved in mitochondrial fatty acid metabolism – was identified as a high-confidence interactor of KCTD14 in a large-scale affinity purification study. In the BioPlex human interactome project (HEK293T cells), KCTD14 pulled down ACSF3 with a very high quantitative score (CompPASS ~0.99, well above significance threshold) (thebiogrid.org) (thebiogrid.org). This interaction was consistently observed across multiple dataset versions (BioPlex 1.0, 2.0, 3.0) (thebiogrid.org), suggesting a robust association. ACSF3 is a mitochondrial matrix enzyme; if KCTD14 binds ACSF3, it could hint at a role in regulating metabolic enzymes (for instance, by ubiquitination or localization).
TUBGCP6 (Tubulin gamma complex-associated protein 6) – a component of the γ-tubulin ring complex involved in microtubule nucleation at centrosomes – was also co-purified with KCTD14 in the BioPlex screen, with a similarly high interaction score (~0.98) (thebiogrid.org). This suggests KCTD14 might associate with centrosomal or cytoskeletal structures, possibly influencing cell cycle or mitotic spindle organization if the interaction is functional.
These partners are notable because they point toward disparate cellular processes (mitochondrial metabolism and microtubule organization). It is not yet confirmed whether KCTD14 directly regulates these proteins, but such protein–protein interaction data provide testable hypotheses. At minimum, they reinforce that KCTD14 is engaged in protein networks inside the cell rather than acting alone. In addition to these interactions, KCTD14 is presumed to partake in broader protein complexes by virtue of its oligomerization and possible co-adaptor behavior. Overall, while KCTD14’s primary molecular function has not been definitively demonstrated, the current understanding is that it likely serves as a scaffold or adaptor protein, potentially in ubiquitin-mediated proteostasis pathways or other multi-protein complexes. This is supported by the consensus that KCTD family members “use their C-termini to bind and recruit diverse cellular proteins destined for degradation” in partnership with Cullin3 complexes (pmc.ncbi.nlm.nih.gov) (a model that KCTD14 may partially follow, albeit in an atypical way).
Knowing where a protein is expressed and localized can provide insight into its function. KCTD14 is an intracellular protein with a broad tissue distribution. It has no signal peptide or transmembrane segment, and experiments confirm it resides inside cells (not secreted) (www.proteinatlas.org). In immunohistochemistry/immunofluorescence analyses, KCTD14 protein shows cytosolic and nucleoplasmic localization (www.proteinatlas.org). Specifically, the Human Protein Atlas reports KCTD14 concentrated in the nucleoplasm (nuclear interior) and also in the cytosol and vesicle-like structures (www.proteinatlas.org). The vesicular staining could indicate presence on or near certain organelles or protein complexes (for example, it might associate with vesicular bodies or mitochondria, consistent with its interaction with a mitochondrial enzyme). The nucleoplasmic presence suggests KCTD14 might shuttle to the nucleus or interact with nuclear proteins, though its role there is undefined. It is not known to bind DNA directly (no DNA-binding domains), but it could influence nuclear processes indirectly via protein interactions.
At the tissue level, KCTD14 mRNA is expressed in many tissues without extreme specificity. RNA profiling (NCBI and GTEx data) shows broad expression: for instance, moderate levels in adrenal gland (RPKM ~10) and stomach (RPKM ~9.5), among at least 17 tissues examined (www.ncbi.nlm.nih.gov). The expression is “low tissue specificity”, meaning KCTD14 is fairly ubiquitously expressed rather than restricted to a particular organ or cell type (www.proteinatlas.org). Nonetheless, some enrichment has been noted in certain cell types: single-cell RNA data indicate higher expression in epithelial secretory cells (e.g. breast glandular cells, stomach foveolar cells, epididymal cells, alveolar type II lung cells) (www.proteinatlas.org). This clustering in secretory/glandular cell types could be a clue to function – perhaps KCTD14 is involved in protein processing or vesicle trafficking, as those cells have high secretory activity. In fact, KCTD14’s expression pattern groups with a cluster of genes related to “protein processing” in the Human Protein Atlas analysis (www.proteinatlas.org). It is not detected in blood plasma and shows no enrichment in immune cells (www.proteinatlas.org), aligning with it being a intracellular, ubiquitously expressed regulator rather than a secreted factor or cytokine.
In summary, the subcellular localization and expression data suggest KCTD14 operates in the general cellular machinery present in many cell types. Its presence in both the nucleus and cytosol indicates a potentially shuttling or multi-functional protein. Given these locations, KCTD14 could influence processes ranging from protein degradation (often cytosolic) to cell cycle or gene expression (nuclear) – consistent with the diverse identities of its candidate interacting partners (mitochondrial enzyme vs. centrosomal protein). However, pinpointing the exact cellular process requires more targeted studies.
Because KCTD14 has only recently begun to attract research interest, its precise biological role is not fully established. Unlike some KCTD family members (e.g. KCTD13 implicated in neurodevelopmental disorders, KCTD7 in epilepsy, KCTD11 in cancer (pmc.ncbi.nlm.nih.gov)), KCTD14 has not yet been definitively linked to a specific disease or phenotype. There are no known inherited mutations in KCTD14 causing a human genetic syndrome, and KCTD14 knockout mouse phenotypes have not been reported in the literature as of 2023. This suggests that KCTD14’s functions might be somewhat redundant or subtle, or simply that it has been under-investigated. However, emerging data hints at some clinical correlations: cancer genomics studies have found that KCTD14 expression levels correlate with patient outcomes in certain cancers. According to the Human Protein Atlas analysis of tumor datasets, KCTD14 is a prognostic marker in at least four cancer types – including kidney renal clear cell carcinoma, pancreatic adenocarcinoma, skin melanoma, and thyroid carcinoma (www.proteinatlas.org). Specifically, differential expression of KCTD14 in these tumors is statistically associated with survival rates (though the direction of risk isn’t specified in the snippet). This association suggests that KCTD14 could play a role in tumor biology, perhaps through its putative function in protein degradation pathways or cell cycle regulation. It’s important to note that being a prognostic marker does not necessarily mean KCTD14 drives cancer progression; it might be part of a broader expression program in tumors. Nonetheless, such findings make KCTD14 a candidate for further research in oncology – understanding how its expression is regulated in cancers and whether it contributes to processes like cell proliferation or stress responses could be valuable.
From a research standpoint, expert opinions highlight the need to characterize proteins like KCTD14 to fill gaps in our understanding of cellular regulation. A 2019 review on the KCTD family pointed out that many KCTDs “remain relatively uncharacterized” and called for deeper investigation into their molecular mechanisms (pmc.ncbi.nlm.nih.gov). The same review and others have pointed out that diverse functions have been proposed for KCTDs, including roles in apoptosis, metabolism, and neural signaling (pmc.ncbi.nlm.nih.gov) (biosignaling.biomedcentral.com). It is thought that the adaptor/scaffold function of KCTDs could underlie these varied roles – by selecting specific protein targets for ubiquitination or by assembling signaling complexes, KCTDs can impact various pathways (pmc.ncbi.nlm.nih.gov). In the case of KCTD14, current hypotheses (drawing from the family context and preliminary data) include:
Proteostasis Regulation: KCTD14 may help target certain proteins (like the ACSF3 enzyme or other yet-unknown substrates) for ubiquitin-mediated degradation. This could affect metabolic enzyme turnover or the stability of proteins involved in cell structure (e.g. tubulin complex components). Supporting this, KCTD14’s close homolog KCTD7 has been linked to the ubiquitin–proteasome system in neurons (pubmed.ncbi.nlm.nih.gov), and loss of KCTD7 causes accumulation of proteins in a neurodegenerative context. It’s conceivable KCTD14 performs a similar function in other cell types.
Cell Cycle or Signaling Scaffold: If the interaction with TUBGCP6 is biologically relevant, KCTD14 might localize to centrosomes or mitotic structures and influence cell division. Alternatively, KCTD14 could have unidentified interactions with signaling proteins (e.g., kinases or receptors) given that some KCTDs modulate G-protein-coupled receptor signaling (notably KCTD12, -16 modulate GABA_B receptors ). No direct evidence yet ties KCTD14 to a specific signaling pathway, but ongoing interactome studies and phenotypic screens (such as CRISPR knockouts in cell lines) may soon illuminate its role. Notably, large-scale screens (DepMap) have not flagged KCTD14 as an essential gene for cell viability in cancer cell lines, but subtler phenotypes are possible.
Compensatory/Redundant Functions: It’s also possible KCTD14 has overlapping function with another KCTD. Given its ability to bind KCTD5, one theory is that KCTD14 could modulate the activity of the Cul3–KCTD5 ubiquitin ligase complex. For example, a KCTD14 subunit in a KCTD5 pentamer might alter which substrate is ubiquitinated or the timing of ubiquitin transfer. Such regulatory crosstalk between KCTD family members is an emerging theme – a recent study showed KCTD12 and KCTD16 form hetero-oligomers that fine-tune GABA_B receptor signaling kinetics (pmc.ncbi.nlm.nih.gov). Similarly, KCTD5’s interplay with other KCTDs influenced their ability to recruit Cul3 (pmc.ncbi.nlm.nih.gov). Investigating whether KCTD14 alters KCTD5’s function (or vice versa) is a current research question.
In latest research (2022–2024), the focus has been on understanding structure and interactions:
- The AlphaFold-based structural analyses (2021–2022) of the entire KCTD family provided a framework for KCTD14’s pentameric structure and highlighted its unusual BTB loop, raising the question about Cul3 binding (www.mdpi.com) (pmc.ncbi.nlm.nih.gov). These computational studies by Esposito et al. and by Balasco et al. (Int. J. Mol. Sci. 2022; Biomolecules 2021) are guiding experimentalists to which aspects of KCTD14’s structure to validate.
- The protein–protein interaction studies (2023), such as Liao et al. (Int. J. Mol. Sci. 2023), systematically probing KCTD5 interactions, have for the first time shown KCTD14 in complex with another family member (pmc.ncbi.nlm.nih.gov). This provides concrete evidence that KCTD14 does not function in isolation and can integrate into known pathways (Cul3 ubiquitination via KCTD5).
- Ongoing high-throughput proteomics (BioPlex 3.0 released in 2021 (thebiogrid.org)) has expanded the list of KCTD14’s candidate partners, which researchers can now follow up individually to test if, for example, KCTD14 regulates the stability or activity of ACSF3 or TUBGCP6 in cells.
In conclusion, KCTD14 is a scaffold-like protein whose known attributes (BTB domain oligomerization, broad expression, intracellular localization) align with a role in orchestrating protein complexes, possibly in ubiquitin-mediated protein turnover. Current evidence points to it forming pentamers and interacting with key cellular proteins, though it may be unique among KCTDs in how it engages the Cul3 ubiquitin ligase pathway. As a relatively uncharted gene, KCTD14’s function is being pieced together from bioinformatic predictions and initial protein-interaction maps. The next steps in research will likely involve targeted experiments: e.g. creating KCTD14-knockout cell lines or animals to see what physiological processes are affected, and biochemical assays to confirm if it directs ubiquitination of specific substrates. Given its emerging links to cancer prognosis and potential partnerships in critical cellular machinery (metabolism and microtubule organization), KCTD14 represents a fascinating example of a “dark” gene now coming to light. Continued investigation, supported by the recent structural and interactome data, should clarify the biological processes governed by KCTD14 and whether it can be leveraged in biomedical contexts (for instance, as a biomarker or a therapeutic target in pathways it regulates). The current understanding, while limited, establishes KCTD14 as an intracellular adaptor protein with a probable role in maintaining protein homeostasis and cellular signaling integrity, operating at the intersection of the ubiquitin-proteasome system and other cellular networks.
References: Recent authoritative sources and data supporting this summary include structural biology analyses of KCTD oligomers (www.mdpi.com) (pmc.ncbi.nlm.nih.gov), reviews on KCTD family functions (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), interaction studies (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov), expression/localization databases (www.proteinatlas.org) (www.ncbi.nlm.nih.gov), and bioinformatic protein network findings (thebiogrid.org) (thebiogrid.org) (referenced in-line above). These up-to-date sources (2019–2023) provide the foundation for the current model of KCTD14 function and will serve as a guide for future experimental exploration.
id: Q9BQ13
gene_symbol: KCTD14
product_type: PROTEIN
status: COMPLETE
taxon:
id: NCBITaxon:9606
label: Homo sapiens
description: KCTD14 encodes a BTB/POZ domain-containing protein that is a member
of the KCTD (potassium channel tetramerization domain-containing) protein
family. The protein contains a T1-type BTB domain (residues 33-130) that is
predicted to mediate pentameric homooligomerization based on family-wide
structural analysis. Unlike many other KCTD family members, recent
AlphaFold-based structural modeling (2024) suggests KCTD14 does NOT form a
stable complex with Cullin3 (Cul3), indicating it may not function as a
canonical CRL3 E3 ubiquitin ligase adaptor. The protein's primary molecular
function remains poorly characterized, though high-throughput interaction
studies have detected associations with STK16, TCF4, and ACSF3. KCTD14 shows
low tissue specificity and has been detected in parotid gland and 138 other
cell types or tissues.
existing_annotations:
- term:
id: GO:0051260
label: protein homooligomerization
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: This annotation is inferred from InterPro domain analysis. The
T1-type BTB domain (IPR003131) in KCTD14 is structurally homologous to
domains that mediate oligomerization in other KCTD family members.
AlphaFold-based structural surveys support that KCTD BTB domains
frequently assemble into pentamers, and KCTD14 is expected to oligomerize
via its BTB domain in keeping with the family trend (Balasco et al. 2024).
action: ACCEPT
reason: The annotation is well-supported by structural homology. The BTB/POZ
domain is a well-characterized oligomerization domain. Family-wide
AlphaFold analyses confirm that KCTD proteins typically form pentameric
assemblies via their BTB domains. While direct experimental evidence for
KCTD14 oligomerization is lacking, the structural prediction is robust
given the high conservation of oligomerization function across BTB
domains.
supported_by:
- reference_id: file:human/KCTD14/KCTD14-deep-research-falcon.md
supporting_text: KCTD14 is expected to oligomerize via its BTB domain,
most commonly as a homopentamer, in keeping with the family trend
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:25416956
review:
summary: This annotation derives from the Rolland et al. 2014 proteome-scale
human interactome map, which used yeast two-hybrid screening to identify
approximately 14,000 high-quality binary protein-protein interactions.
This is a high-throughput study without specific KCTD14-focused
validation.
action: REMOVE
reason: Per curation guidelines, GO:0005515 (protein binding) is
uninformative and should be avoided. The term does not convey any specific
information about the molecular function of KCTD14. The high-throughput
nature of the study means specific interactors were not validated for
KCTD14 individually. If specific binding partners were identified, more
informative molecular function terms should be used instead. The
interaction data itself may be useful but the GO:0005515 annotation is not
informative.
supported_by:
- reference_id: PMID:25416956
supporting_text: Here, we describe a systematic map of ?14,000
high-quality human binary protein-protein interactions
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:28514442
review:
summary: This annotation derives from the BioPlex 2.0 study (Huttlin et al.
2017), which used affinity-purification mass spectrometry (AP-MS) to
identify protein-protein interactions for over 25% of human protein-coding
genes. BioPlex 2.0 contains over 56,000 candidate interactions. This is a
high-throughput proteome-scale study.
action: REMOVE
reason: Per curation guidelines, GO:0005515 (protein binding) is
uninformative and should be avoided. While BioPlex 2.0 is a valuable
resource for identifying potential interaction partners, the generic
protein binding annotation does not convey specific functional information
about KCTD14. The underlying interaction data may be valuable for
characterizing KCTD14 function, but the GO annotation itself is not
informative.
supported_by:
- reference_id: PMID:28514442
supporting_text: BioPlex 2.0 is the largest collection of human co-complex
data assembled from a single pipeline to date, containing 56,553
interactions from 10,961 proteins
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:29892012
review:
summary: This annotation derives from Chen et al. 2018, which established an
interactome perturbation framework to prioritize damaging missense
mutations for developmental disorders. The study analyzed approximately
2,000 de novo missense mutations in the context of the human interactome
network. This is a computational/high-throughput study focused on mutation
effects on interactions rather than direct functional characterization.
action: REMOVE
reason: Per curation guidelines, GO:0005515 (protein binding) is
uninformative and should be avoided. This study was focused on identifying
disease-relevant missense mutations by their effects on protein
interactions, not on characterizing the specific molecular functions of
individual proteins like KCTD14. The generic protein binding annotation
provides no insight into KCTD14's specific function.
supported_by:
- reference_id: PMID:29892012
supporting_text: Here we establish an experimentally and computationally
integrated approach to investigate the functional impact of missense
mutations in the context of the human interactome network
- term:
id: GO:0005515
label: protein binding
evidence_type: IPI
original_reference_id: PMID:33961781
review:
summary: This annotation derives from the BioPlex 3.0/dual network study
(Huttlin et al. 2021), which profiled protein interactions in both 293T
and HCT116 cells using affinity-purification mass spectrometry. BioPlex
3.0 includes 118,162 interactions among 14,586 proteins. This is a
high-throughput proteome-scale study.
action: REMOVE
reason: Per curation guidelines, GO:0005515 (protein binding) is
uninformative and should be avoided. While this dual-network approach
provides valuable context about cell-type-specific interactions, the
generic protein binding annotation does not convey any specific
information about KCTD14's molecular function. If specific binding
partners were validated, more informative terms should be used.
supported_by:
- reference_id: PMID:33961781
supporting_text: BioPlex 3.0, results from affinity purification of 10,128
human proteins-half the proteome-in 293T cells and includes 118,162
interactions among 14,586 proteins
- term:
id: GO:0042802
label: identical protein binding
evidence_type: NAS
review:
summary: Added to align core_functions with existing annotations.
action: NEW
reason: Core function term not present in existing_annotations.
supported_by:
- reference_id: file:human/KCTD14/KCTD14-deep-research-falcon.md
supporting_text: KCTD14 is expected to oligomerize via its BTB domain,
most commonly as a homopentamer, in keeping with the family trend
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with
GO terms
findings:
- statement: KCTD14 contains T1-type BTB domain (IPR003131) associated with
oligomerization
- id: PMID:25416956
title: A proteome-scale map of the human interactome network.
findings:
- statement: High-throughput yeast two-hybrid study identifying approximately
14,000 binary protein-protein interactions
supporting_text: Here, we describe a systematic map of ?14,000 high-quality
human binary protein-protein interactions
- statement: Study focused on generating reference interactome map, not
individual protein characterization
supporting_text: Just as reference genome sequences revolutionized human
genetics, reference maps of interactome networks will be critical to fully
understand genotype-phenotype relationships
- id: PMID:28514442
title: Architecture of the human interactome defines protein communities and
disease networks.
findings:
- statement: BioPlex 2.0 AP-MS study with over 56,000 candidate interactions
supporting_text: BioPlex 2.0 is the largest collection of human co-complex
data assembled from a single pipeline to date, containing 56,553
interactions from 10,961 proteins
- statement: BTB domains like those in KCTD proteins associated with
Cullin-RING E3 ubiquitin ligase system
supporting_text: The cullin domain was paired de novo with 15 additional
domains, many of which also co-associated... Neighbors of proteins
containing RBX1/2-binding cullin homology domains were enriched with BTB,
BTB_2, SOCS and FBOX domains known to bind the cullin N-terminal domain
- id: PMID:29892012
title: An interactome perturbation framework prioritizes damaging missense
mutations for developmental disorders.
findings:
- statement: Computational framework for analyzing effects of missense
mutations on protein interactions
supporting_text: Here we establish an experimentally and computationally
integrated approach to investigate the functional impact of missense
mutations in the context of the human interactome network
- statement: Study focused on autism and developmental disorders
supporting_text: test our approach by analyzing ~2,000 de novo missense
mutations found in autism subjects and their unaffected siblings
- id: PMID:33961781
title: Dual proteome-scale networks reveal cell-specific remodeling of the
human interactome.
findings:
- statement: BioPlex 3.0 with 118,162 interactions in 293T cells
supporting_text: BioPlex 3.0, results from affinity purification of 10,128
human proteins-half the proteome-in 293T cells and includes 118,162
interactions among 14,586 proteins
- statement: Comparison of context-specific interactome networks
supporting_text: performing AP-MS in 293T and HCT116 cells has enabled
comparison of two context-specific, proteome-scale interaction networks
- id: file:human/KCTD14/KCTD14-deep-research-falcon.md
title: Deep research summary for KCTD14
findings:
- statement: KCTD14 BTB domain does not form stable complex with Cullin3 in
AlphaFold-based modeling
supporting_text: The 2024 AF survey explicitly reports "no stable complex
detected" for KCTD14-Cul3 under a 5:5 symmetry assumption for the BTB-Cul3
assembly
- statement: KCTD14 is predicted NOT to be a canonical CRL3 adaptor based on
structural analysis
supporting_text: AF-based modeling found no stable Cul3 binding, arguing
against a canonical CRL3 adaptor role
- statement: KCTD proteins typically form pentameric assemblies via BTB
domains
supporting_text: KCTD14 is expected to oligomerize via its BTB domain, most
commonly as a homopentamer, in keeping with the family trend
- statement: KCTD14 clusters structurally with KCTD7 based on fold similarity
supporting_text: AlphaFold-derived pseudo-phylogenetic analysis reported a
specific structural pairing of KCTD7 with KCTD14
- id: file:human/KCTD14/KCTD14-deep-research-cyberian.md
title: Cyberian deep research on KCTD14 function
findings: []
core_functions:
- description: KCTD14 forms homooligomeric assemblies via its BTB domain, likely
as pentamers based on family-wide structural analysis. The primary molecular
function beyond oligomerization remains to be determined experimentally.
molecular_function:
id: GO:0042802
label: identical protein binding
directly_involved_in:
- id: GO:0051260
label: protein homooligomerization
supported_by:
- reference_id: file:human/KCTD14/KCTD14-deep-research-falcon.md
supporting_text: KCTD14 is expected to oligomerize via its BTB domain, most
commonly as a homopentamer, in keeping with the family trend
suggested_questions:
- question: What are the specific binding partners of KCTD14 and what biological
processes do these interactions serve?
- question: Does KCTD14 have any scaffolding or regulatory functions independent
of Cullin3?
- question: What is the subcellular localization of KCTD14 in different cell
types?
- question: Does KCTD14 interact with STK16 and TCF4 in vivo and what are the
functional consequences of these interactions?
suggested_experiments:
- description: Co-immunoprecipitation or proximity labeling (BioID/APEX) to
identify and validate specific interaction partners
- description: Immunofluorescence or subcellular fractionation to determine
cellular localization
- description: CRISPR knockout or knockdown studies to identify phenotypic
consequences
- description: Biochemical characterization of oligomeric state using size
exclusion chromatography or native PAGE