{"gene":"KCTD5","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2008,"finding":"KCTD5 interacts specifically with Cullin3 via its BTB domain plus additional N-terminal residues, binds ubiquitinated proteins, and forms oligomers through its BTB domain, establishing it as a putative substrate-specific adaptor for Cullin3-based E3 ligases. KCTD5 was found in the cytosol of cultured cell lines.","method":"Co-immunoprecipitation, binding assays, mutagenesis of BTB/N-terminal residues, subcellular fractionation","journal":"The FEBS journal","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and mutagenesis in single lab; BTB domain and N-terminal residues required for Cullin3 binding demonstrated by multiple methods","pmids":["18573101"],"is_preprint":false},{"year":2023,"finding":"KCTD5 assembles as a pentamer and, in complex with Cullin3, ubiquitinates Gβγ subunits; cryo-EM structure shows five copies of Gβγ engaged symmetrically through KCTD5's C-terminal domain, enabling simultaneous ubiquitin transfer from the E2 enzyme to five Gβγ subunits. KCTD5-mediated Gβγ ubiquitination negatively regulates cAMP signaling downstream of GPCRs.","method":"Cryo-electron microscopy structure determination, ubiquitination assays, cAMP signaling assays","journal":"Science advances","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure with functional validation of ubiquitination and downstream cAMP signaling, corroborated by independent study (PMID:38625940)","pmids":["37450587"],"is_preprint":false},{"year":2024,"finding":"Cryo-EM structure of the 5:5:5 KCTD5/CUL3NTD/Gβ1γ2 assembly reveals a highly dynamic complex with >60° rotational freedom between BTB and CTD moieties; CRL3KCTD5 engages the E3 ligase ARIH1 in an E3-E3 superassembly to ubiquitylate Gβγ, with conformational states positioning the ARIH1~ubiquitin thioester bond within ~10 Å of Lys-23 of Gβ as likely priming complexes.","method":"Cryo-EM structure determination, ubiquitylation assays, structural modeling of full-length CUL3/RBX1/ARIH1~ubiquitin conjugate","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 / Strong — cryo-EM structure with multiple orthogonal methods including ubiquitylation assays; independently corroborates PMID:37450587","pmids":["38625940"],"is_preprint":false},{"year":2015,"finding":"KCTD5 interacts with MCM7, ZNF711, and FAM193B, forming trimeric complexes with Cullin3; however, KCTD5/Cullin3 did not induce polyubiquitylation or proteasome-dependent degradation of these partners. Instead, KCTD5 or Cullin3 overexpression increased ZNF711 protein stability, suggesting a role in protein stabilization rather than degradation for some substrates.","method":"Yeast two-hybrid, co-immunoprecipitation in mammalian cells, proteasome inhibitor assays, overexpression experiments","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and yeast two-hybrid, two orthogonal methods, single lab","pmids":["26188516"],"is_preprint":false},{"year":2015,"finding":"Molecular dynamics simulations of KCTD5 reveal that the pentameric CTD assembly is intrinsically stable, and that large interdomain twisting motions between the BTB and CTD domains are pivoted by a single hinge residue (Ser150), potentially positioning substrates for ubiquitination.","method":"Molecular dynamics simulations (120 ns) of full-length KCTD5 pentamer","journal":"Journal of biomolecular structure & dynamics","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational simulation only, no experimental validation of Ser150 functional role","pmids":["26336981"],"is_preprint":false},{"year":2018,"finding":"KCTD5 physically interacts with ΔNp63α, and the Cullin3/KCTD5 complex induces monoubiquitination (not polyubiquitination) of ΔNp63α, reducing its DNA-binding affinity and impairing both its transactivation and transinhibitory activities, thereby attenuating ΔNp63α-driven cell proliferation.","method":"Co-immunoprecipitation, ubiquitination assays, DNA-binding assays, reporter/transactivation assays, cell proliferation assays","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, in vivo ubiquitination assays, and functional readouts in single lab with multiple orthogonal methods","pmids":["29782646"],"is_preprint":false},{"year":2020,"finding":"KCTD5 binds RhoGDI1 and increases its interaction with CUL3; ectopic KCTD5 expression increases RhoGDI1 ubiquitination, whereas KCTD5 knockdown stabilizes RhoGDI1 and reduces its ubiquitination, establishing CUL3/KCTD5 as an E3 ligase complex that targets RhoGDI1 for degradation.","method":"Co-immunoprecipitation, ubiquitination assays, RNA interference knockdown, dominant-negative CUL3 expression, stability assays","journal":"Journal of microbiology and biotechnology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, and KD/DN rescue in single lab with multiple methods","pmids":["32876072"],"is_preprint":false},{"year":2020,"finding":"CRISPR/Cas9 and shRNA depletion of KCTD5 in B16-F10 cells increases cell migration, cell spreading, and focal adhesion disassembly rate. These effects are mediated through Rac1 GTPase activity (dominant-negative Rac1 rescues spreading) and Ca2+ signaling (KCTD5 loss decreases serum-induced Ca2+ response; ionomycin reversal restores focal adhesion size).","method":"CRISPR/Cas9 knockout, shRNA knockdown, live-cell imaging, dominant-negative Rac1 expression, Ca2+ imaging, focal adhesion dynamics assays","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic KO with multiple orthogonal functional assays and dominant-negative rescue, single lab","pmids":["33053687"],"is_preprint":false},{"year":2017,"finding":"KCTD5 itself is ubiquitinated and degraded by the proteasome in AGS gastric epithelial cells; H. pylori infection impairs KCTD5 ubiquitination, reducing KCTD5 levels. Decreased KCTD5 (an adaptor of Cullin-3) increases H. pylori adherence, indicating KCTD5 proteasomal turnover is exploited by the pathogen to facilitate colonization.","method":"Ubiquitination assays, proteasome inhibitor experiments, H. pylori infection assays, RNA interference knockdown, adherence assays","journal":"Frontiers in cellular and infection microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ubiquitination assays and KD with specific adherence phenotype, single lab, multiple methods","pmids":["29114497"],"is_preprint":false},{"year":2023,"finding":"KCTD5 forms hetero-oligomeric complexes with numerous other KCTD family members (including KCTD2, KCTD17, and others); different regions of KCTD5 contribute distinctly to interactions with different KCTD partners.","method":"Co-immunoprecipitation, BRET (bioluminescence resonance energy transfer) in live cells, IP-luminescence domain-mapping assays","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP corroborated by live-cell BRET, single lab, two orthogonal methods","pmids":["37762619"],"is_preprint":false},{"year":2024,"finding":"KCTD5 is identified as a key stabilizing factor for Ikaros transcription factor; etoposide treatment decreases the KCTD5-Ikaros interaction, leading to accelerated Ikaros protein degradation (affecting IK1, IK2, IK4 isoforms but not IK6/IK7) in leukemic cells.","method":"Immunoprecipitation coupled with LC-MS/MS, co-immunoprecipitation, protein stability/degradation assays, etoposide treatment experiments","journal":"Biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — IP/MS discovery followed by Co-IP validation and stability assays, single lab, two orthogonal methods","pmids":["38424700"],"is_preprint":false},{"year":2025,"finding":"Conditional knockout of Kctd5 in striatal neurons in mice leads to dystonic phenotype, coordination deficits, and augmented electrically evoked cAMP responses to dopaminergic stimulation. Rescue by a Gβγ-scavenging nanobody confirms KCTD5 acts as a brake on Gβγ-mediated cAMP signaling in striatal circuits, and motor deficits are partially rescued by pharmacological antagonism of the indirect striatal cAMP pathway.","method":"Conditional knockout mouse (Cre-lox), 2-photon cAMP biosensor imaging, Gβγ-scavenging nanobody rescue, pharmacological rescue, behavioral assays","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional KO with in vivo imaging, nanobody rescue, and pharmacological rescue across multiple orthogonal methods in single rigorous study","pmids":["40233107"],"is_preprint":false},{"year":2025,"finding":"Heterozygous Kctd5 knockout mice (Kctd5-/- embryos are lethal in early embryonic development) exhibit abnormal lipid metabolism including elevated cholesterol and triglycerides; genome-wide expression analysis suggests KCTD5 affects the PPAR signaling pathway and expression of Apolipoprotein family genes to regulate lipid metabolism.","method":"CRISPR/Cas9 heterozygous knockout mice, metabolic profiling, genome-wide gene expression analysis","journal":"The international journal of biochemistry & cell biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — KO phenotype with transcriptomic pathway inference but no direct mechanistic validation of PPAR/Apo pathway regulation","pmids":["40846050"],"is_preprint":false},{"year":2026,"finding":"KCTD5 acts as a positive regulator of TRPM4 channel activity, increasing Ca2+ sensitivity; peptides designed to disrupt the TRPM4-KCTD5 protein-protein interface reduce TRPM4-dependent Na+ influx and currents and decrease cell invasion in MDA-MB-231 cells, confirming the functional importance of this interaction.","method":"BiFC (bimolecular fluorescent complementation), patch clamp electrophysiology, intracellular Na+ recordings, CRISPR KCTD5 knockout cells (HEK293KCTD5-/-), cell invasion assays","journal":"Journal of chemical information and modeling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — BiFC interaction assay corroborated by electrophysiology and KO cells with multiple functional readouts, single lab","pmids":["42214084"],"is_preprint":false}],"current_model":"KCTD5 is a pentameric BTB-domain protein that functions as a substrate-specific adaptor for Cullin3-RING E3 ubiquitin ligase complexes (CRL3KCTD5), recruiting substrates including Gβγ subunits (triggering their ubiquitination and degradation via an ARIH1 E3-E3 superassembly), RhoGDI1, ΔNp63α (monoubiquitination), and Ikaros (stabilization), thereby acting as a molecular brake on Gβγ-mediated cAMP signaling in striatal neurons important for motor coordination, while also regulating cell migration through modulation of Rac1 activity, focal adhesion dynamics, and Ca2+ signaling via TRPM4."},"narrative":{"mechanistic_narrative":"KCTD5 is a pentameric BTB-domain protein that serves as a substrate-specific adaptor for Cullin3-RING E3 ubiquitin ligase complexes, coupling substrate recognition to ubiquitin transfer [PMID:18573101, PMID:37450587]. It oligomerizes through its BTB domain and engages Cullin3 via the BTB plus additional N-terminal residues, while its C-terminal domain captures substrate [PMID:18573101, PMID:37450587]. Its best-characterized substrate is the heterotrimeric G protein Gβγ dimer: cryo-EM of the symmetric 5:5:5 KCTD5/CUL3/Gβγ assembly shows five Gβγ engaged simultaneously, and CRL3KCTD5 recruits the RING-between-RING ligase ARIH1 in an E3-E3 superassembly that primes ubiquitin transfer onto Gβ, thereby negatively regulating cAMP signaling downstream of GPCRs [PMID:37450587, PMID:38625940]. In vivo, conditional deletion of Kctd5 in striatal neurons produces a dystonic, motor-incoordinate phenotype with augmented dopaminergic cAMP responses that is rescued by a Gβγ-scavenging nanobody, establishing KCTD5 as a physiological brake on Gβγ-mediated cAMP signaling in striatal circuits [PMID:40233107]. Beyond Gβγ, KCTD5/CUL3 acts on additional substrates with distinct outcomes: degradative ubiquitination of RhoGDI1 [PMID:32876072], monoubiquitination of ΔNp63α that reduces its DNA binding and proliferative activity [PMID:29782646], and stabilization rather than degradation of partners including ZNF711 and the Ikaros transcription factor [PMID:26188516, PMID:38424700]. KCTD5 also regulates the actin cytoskeleton and cell migration through Rac1 activity, focal adhesion dynamics, and Ca2+ signaling [PMID:33053687], and positively regulates TRPM4 channel Ca2+ sensitivity through a defined protein-protein interface that promotes cell invasion [PMID:42214084]. It forms hetero-oligomers with other KCTD family members, and its own levels are controlled by proteasomal turnover [PMID:29114497, PMID:37762619].","teleology":[{"year":2008,"claim":"Established the founding hypothesis that KCTD5 is a Cullin3 substrate adaptor rather than a passive BTB protein, defining the structural determinants of the interaction.","evidence":"Co-IP, binding assays, and BTB/N-terminal mutagenesis in cultured cells","pmids":["18573101"],"confidence":"Medium","gaps":["No substrate identified at this stage","Ubiquitination activity not directly demonstrated","Single-lab reciprocal Co-IP"]},{"year":2015,"claim":"Showed that not all KCTD5/Cullin3 partners are degraded, revealing a non-degradative, stabilizing mode of action for some substrates.","evidence":"Yeast two-hybrid, Co-IP, and proteasome inhibitor/overexpression assays identifying MCM7, ZNF711, FAM193B","pmids":["26188516"],"confidence":"Medium","gaps":["Mechanism of stabilization not defined","Physiological relevance of these partners unclear","No ubiquitination observed despite complex formation"]},{"year":2015,"claim":"Proposed how the pentameric assembly could position substrates by modeling interdomain motion, framing a structural basis for catalysis.","evidence":"120 ns molecular dynamics simulation of full-length KCTD5 pentamer identifying Ser150 hinge","pmids":["26336981"],"confidence":"Low","gaps":["Computational only; Ser150 role not experimentally validated","No substrate present in simulation"]},{"year":2017,"claim":"Demonstrated that KCTD5 levels are themselves regulated by ubiquitin-proteasome turnover and that a pathogen exploits this to aid colonization.","evidence":"Ubiquitination/proteasome inhibitor assays, knockdown, and H. pylori adherence assays in gastric epithelial cells","pmids":["29114497"],"confidence":"Medium","gaps":["E3 ligase responsible for KCTD5 turnover not identified","Mechanism linking KCTD5 loss to adherence not resolved"]},{"year":2018,"claim":"Identified ΔNp63α as a substrate and showed KCTD5 imposes a regulatory monoubiquitination that tunes transcription factor activity rather than destroying it.","evidence":"Co-IP, ubiquitination, DNA-binding, transactivation reporter, and proliferation assays","pmids":["29782646"],"confidence":"Medium","gaps":["Monoubiquitination site not mapped","Single-lab functional readouts"]},{"year":2020,"claim":"Expanded the degradative substrate set to RhoGDI1 and connected KCTD5 to cytoskeletal regulation via Rac1 and Ca2+ signaling in migration.","evidence":"Co-IP, ubiquitination, KD/dominant-negative rescue, and CRISPR KO with live-cell imaging and Ca2+ imaging","pmids":["32876072","33053687"],"confidence":"Medium","gaps":["Direct link between RhoGDI1 degradation and the migration phenotype not fully established","Mechanism of KCTD5 effect on Ca2+ entry undefined"]},{"year":2023,"claim":"Resolved the central mechanistic question of how KCTD5 acts catalytically, showing a pentameric CRL3KCTD5 engages five Gβγ symmetrically to ubiquitinate them and suppress cAMP signaling.","evidence":"Cryo-EM structure with ubiquitination and cAMP signaling assays","pmids":["37450587"],"confidence":"High","gaps":["In vivo physiological role not yet tested at this stage","How E2 delivery is coordinated across five sites not detailed"]},{"year":2023,"claim":"Demonstrated KCTD5 forms hetero-oligomers with other KCTD family members, implying combinatorial adaptor assemblies.","evidence":"Co-IP, live-cell BRET, and IP-luminescence domain mapping","pmids":["37762619"],"confidence":"Medium","gaps":["Functional consequence of heteromerization for substrate selection unknown","Stoichiometry of mixed oligomers not defined"]},{"year":2024,"claim":"Defined the catalytic geometry by showing CRL3KCTD5 recruits ARIH1 in an E3-E3 superassembly that positions the ubiquitin thioester near Gβ Lys-23, explaining priming of transfer.","evidence":"Cryo-EM of the dynamic 5:5:5 assembly with ubiquitylation assays and modeling of CUL3/RBX1/ARIH1~ubiquitin","pmids":["38625940"],"confidence":"High","gaps":["Processivity and chain-type specificity not fully resolved","Role of >60° interdomain dynamics in turnover not directly tested"]},{"year":2024,"claim":"Established a stabilizing role in leukemic cells by identifying KCTD5 as a factor that protects Ikaros isoforms from degradation under genotoxic stress.","evidence":"IP-LC-MS/MS, Co-IP, and protein stability assays with etoposide treatment","pmids":["38424700"],"confidence":"Medium","gaps":["Molecular basis of stabilization versus degradation choice unresolved","Isoform selectivity mechanism unknown"]},{"year":2025,"claim":"Provided in vivo validation that KCTD5 is a physiological brake on Gβγ-mediated cAMP signaling required for motor coordination.","evidence":"Striatal conditional KO mice with 2-photon cAMP imaging, Gβγ-scavenging nanobody rescue, pharmacological rescue, and behavior","pmids":["40233107"],"confidence":"High","gaps":["Cell-type-specific substrate scope in vivo beyond Gβγ untested","Link to dystonia mechanism only partially defined"]},{"year":2025,"claim":"Indicated a developmental and metabolic role, with embryonic lethality of full knockout and lipid-metabolism abnormalities in heterozygotes.","evidence":"CRISPR heterozygous KO mice, metabolic profiling, genome-wide expression analysis","pmids":["40846050"],"confidence":"Low","gaps":["PPAR/Apolipoprotein pathway link is transcriptomic inference without mechanistic validation","Direct substrate driving the lipid phenotype not identified"]},{"year":2026,"claim":"Showed KCTD5 acts as a positive regulator of an ion channel, increasing TRPM4 Ca2+ sensitivity through a definable interface that promotes invasion.","evidence":"BiFC, patch clamp, intracellular Na+ recordings, CRISPR KO cells, interface-disrupting peptides, and invasion assays","pmids":["42214084"],"confidence":"Medium","gaps":["Whether regulation is ubiquitination-dependent unclear","Structural basis of the TRPM4-KCTD5 interface not solved"]},{"year":null,"claim":"How KCTD5 chooses between degradative polyubiquitination, regulatory monoubiquitination, substrate stabilization, and ubiquitination-independent channel modulation across its diverse partners remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying rule distinguishes degraded versus stabilized substrates","Contribution of KCTD heteromerization to substrate choice unknown","Tissue-specific substrate repertoire largely uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,2,5,6]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[1,2,6]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[0,1]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[11,13]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[1,2,6]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,11]}],"complexes":["CRL3KCTD5 (Cullin3-RING E3 ligase)","CRL3KCTD5-ARIH1 E3-E3 superassembly"],"partners":["CUL3","ARIH1","GNB1","ARHGDIA","TP63","IKZF1","TRPM4","KCTD17"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9NXV2","full_name":"BTB/POZ domain-containing protein KCTD5","aliases":[],"length_aa":234,"mass_kda":26.1,"function":"Its interaction with CUL3 suggests that it may act as a substrate adapter in some E3 ligase complex (PubMed:18573101). Does not affect the function of Kv channel Kv2.1/KCNB1, Kv1.2/KCNA2, Kv4.2/KCND2 and Kv3.4/KCNC4 (PubMed:19361449)","subcellular_location":"Cytoplasm, cytosol; Cytoplasm; Nucleus","url":"https://www.uniprot.org/uniprotkb/Q9NXV2/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCTD5","classification":"Not Classified","n_dependent_lines":98,"n_total_lines":1208,"dependency_fraction":0.08112582781456953},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/KCTD5","total_profiled":1310},"omim":[{"mim_id":"611285","title":"POTASSIUM CHANNEL TETRAMERIZATION DOMAIN-CONTAINING PROTEIN 5; KCTD5","url":"https://www.omim.org/entry/611285"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KCTD5"},"hgnc":{"alias_symbol":["FLJ20040"],"prev_symbol":[]},"alphafold":{"accession":"Q9NXV2","domains":[{"cath_id":"3.30.710.10","chopping":"46-150","consensus_level":"high","plddt":91.5983,"start":46,"end":150},{"cath_id":"3.30.70.2000","chopping":"153-191_198-212","consensus_level":"medium","plddt":86.9052,"start":153,"end":212}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NXV2","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NXV2-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9NXV2-F1-predicted_aligned_error_v6.png","plddt_mean":77.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCTD5","jax_strain_url":"https://www.jax.org/strain/search?query=KCTD5"},"sequence":{"accession":"Q9NXV2","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9NXV2.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9NXV2/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9NXV2"}},"corpus_meta":[{"pmid":"18573101","id":"PMC_18573101","title":"KCTD5, a putative substrate adaptor for cullin3 ubiquitin ligases.","date":"2008","source":"The FEBS journal","url":"https://pubmed.ncbi.nlm.nih.gov/18573101","citation_count":77,"is_preprint":false},{"pmid":"37450587","id":"PMC_37450587","title":"Structural basis for the ubiquitination of G protein βγ subunits by KCTD5/Cullin3 E3 ligase.","date":"2023","source":"Science advances","url":"https://pubmed.ncbi.nlm.nih.gov/37450587","citation_count":24,"is_preprint":false},{"pmid":"33053687","id":"PMC_33053687","title":"K+ Channel Tetramerization Domain 5 (KCTD5) Protein Regulates Cell Migration, Focal Adhesion Dynamics and Spreading through Modulation of Ca2+ Signaling and Rac1 Activity.","date":"2020","source":"Cells","url":"https://pubmed.ncbi.nlm.nih.gov/33053687","citation_count":14,"is_preprint":false},{"pmid":"38625940","id":"PMC_38625940","title":"Structure and dynamics of a pentameric KCTD5/CUL3/Gβγ E3 ubiquitin ligase complex.","date":"2024","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/38625940","citation_count":13,"is_preprint":false},{"pmid":"26188516","id":"PMC_26188516","title":"Interactions of cullin3/KCTD5 complexes with both cytoplasmic and nuclear proteins: Evidence for a role in protein stabilization.","date":"2015","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/26188516","citation_count":13,"is_preprint":false},{"pmid":"29782646","id":"PMC_29782646","title":"Cullin3/KCTD5 induces monoubiquitination of ΔNp63α and impairs its activity.","date":"2018","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/29782646","citation_count":12,"is_preprint":false},{"pmid":"37149576","id":"PMC_37149576","title":"Identifies KCTD5 as a novel cancer biomarker associated with programmed cell death and chemotherapy drug sensitivity.","date":"2023","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/37149576","citation_count":11,"is_preprint":false},{"pmid":"37762619","id":"PMC_37762619","title":"KCTD5 Forms Hetero-Oligomeric Complexes with Various Members of the KCTD Protein Family.","date":"2023","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/37762619","citation_count":11,"is_preprint":false},{"pmid":"26336981","id":"PMC_26336981","title":"KCTD5 is endowed with large, functionally relevant, interdomain motions.","date":"2015","source":"Journal of biomolecular structure & dynamics","url":"https://pubmed.ncbi.nlm.nih.gov/26336981","citation_count":9,"is_preprint":false},{"pmid":"32876072","id":"PMC_32876072","title":"Cullin 3/KCTD5 Promotes the Ubiqutination of Rho Guanine Nucleotide Dissociation Inhibitor 1 and Regulates Its Stability.","date":"2020","source":"Journal of microbiology and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/32876072","citation_count":8,"is_preprint":false},{"pmid":"29114497","id":"PMC_29114497","title":"KCTD5 and Ubiquitin Proteasome Signaling Are Required for Helicobacter pylori Adherence.","date":"2017","source":"Frontiers in cellular and infection microbiology","url":"https://pubmed.ncbi.nlm.nih.gov/29114497","citation_count":7,"is_preprint":false},{"pmid":"39027992","id":"PMC_39027992","title":"CD8+ T cell‑related KCTD5 contributes to malignant progression and unfavorable clinical outcome of patients with triple‑negative breast cancer.","date":"2024","source":"Molecular medicine reports","url":"https://pubmed.ncbi.nlm.nih.gov/39027992","citation_count":2,"is_preprint":false},{"pmid":"40233107","id":"PMC_40233107","title":"The G protein modifier KCTD5 tunes the decoding of neuromodulatory signals necessary for motor function in striatal neurons.","date":"2025","source":"PLoS biology","url":"https://pubmed.ncbi.nlm.nih.gov/40233107","citation_count":2,"is_preprint":false},{"pmid":"40846050","id":"PMC_40846050","title":"Heterozygous Kctd5 knockout mice exhibit abnormal lipid metabolism.","date":"2025","source":"The international journal of biochemistry & cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/40846050","citation_count":0,"is_preprint":false},{"pmid":"38424700","id":"PMC_38424700","title":"KCTD5 regulates Ikaros degradation induced by chemotherapeutic drug etoposide in hematological cells.","date":"2024","source":"Biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/38424700","citation_count":0,"is_preprint":false},{"pmid":"42214084","id":"PMC_42214084","title":"Design of Inhibitory Peptides Based on TRPM4-KCTD5 Interaction.","date":"2026","source":"Journal of chemical information and modeling","url":"https://pubmed.ncbi.nlm.nih.gov/42214084","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9776,"output_tokens":3724,"usd":0.042594,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11404,"output_tokens":4194,"usd":0.080935,"stage2_stop_reason":"end_turn"},"total_usd":0.123529,"stage1_batch_id":"msgbatch_01BbTCMyrRPyhtEq6b1MdwCN","stage2_batch_id":"msgbatch_011dEed5bbxYvTAaQWKJevxu","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"KCTD5 interacts specifically with Cullin3 via its BTB domain plus additional N-terminal residues, binds ubiquitinated proteins, and forms oligomers through its BTB domain, establishing it as a putative substrate-specific adaptor for Cullin3-based E3 ligases. KCTD5 was found in the cytosol of cultured cell lines.\",\n      \"method\": \"Co-immunoprecipitation, binding assays, mutagenesis of BTB/N-terminal residues, subcellular fractionation\",\n      \"journal\": \"The FEBS journal\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and mutagenesis in single lab; BTB domain and N-terminal residues required for Cullin3 binding demonstrated by multiple methods\",\n      \"pmids\": [\"18573101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"KCTD5 assembles as a pentamer and, in complex with Cullin3, ubiquitinates Gβγ subunits; cryo-EM structure shows five copies of Gβγ engaged symmetrically through KCTD5's C-terminal domain, enabling simultaneous ubiquitin transfer from the E2 enzyme to five Gβγ subunits. KCTD5-mediated Gβγ ubiquitination negatively regulates cAMP signaling downstream of GPCRs.\",\n      \"method\": \"Cryo-electron microscopy structure determination, ubiquitination assays, cAMP signaling assays\",\n      \"journal\": \"Science advances\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure with functional validation of ubiquitination and downstream cAMP signaling, corroborated by independent study (PMID:38625940)\",\n      \"pmids\": [\"37450587\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Cryo-EM structure of the 5:5:5 KCTD5/CUL3NTD/Gβ1γ2 assembly reveals a highly dynamic complex with >60° rotational freedom between BTB and CTD moieties; CRL3KCTD5 engages the E3 ligase ARIH1 in an E3-E3 superassembly to ubiquitylate Gβγ, with conformational states positioning the ARIH1~ubiquitin thioester bond within ~10 Å of Lys-23 of Gβ as likely priming complexes.\",\n      \"method\": \"Cryo-EM structure determination, ubiquitylation assays, structural modeling of full-length CUL3/RBX1/ARIH1~ubiquitin conjugate\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — cryo-EM structure with multiple orthogonal methods including ubiquitylation assays; independently corroborates PMID:37450587\",\n      \"pmids\": [\"38625940\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"KCTD5 interacts with MCM7, ZNF711, and FAM193B, forming trimeric complexes with Cullin3; however, KCTD5/Cullin3 did not induce polyubiquitylation or proteasome-dependent degradation of these partners. Instead, KCTD5 or Cullin3 overexpression increased ZNF711 protein stability, suggesting a role in protein stabilization rather than degradation for some substrates.\",\n      \"method\": \"Yeast two-hybrid, co-immunoprecipitation in mammalian cells, proteasome inhibitor assays, overexpression experiments\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and yeast two-hybrid, two orthogonal methods, single lab\",\n      \"pmids\": [\"26188516\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Molecular dynamics simulations of KCTD5 reveal that the pentameric CTD assembly is intrinsically stable, and that large interdomain twisting motions between the BTB and CTD domains are pivoted by a single hinge residue (Ser150), potentially positioning substrates for ubiquitination.\",\n      \"method\": \"Molecular dynamics simulations (120 ns) of full-length KCTD5 pentamer\",\n      \"journal\": \"Journal of biomolecular structure & dynamics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational simulation only, no experimental validation of Ser150 functional role\",\n      \"pmids\": [\"26336981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"KCTD5 physically interacts with ΔNp63α, and the Cullin3/KCTD5 complex induces monoubiquitination (not polyubiquitination) of ΔNp63α, reducing its DNA-binding affinity and impairing both its transactivation and transinhibitory activities, thereby attenuating ΔNp63α-driven cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, DNA-binding assays, reporter/transactivation assays, cell proliferation assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, in vivo ubiquitination assays, and functional readouts in single lab with multiple orthogonal methods\",\n      \"pmids\": [\"29782646\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"KCTD5 binds RhoGDI1 and increases its interaction with CUL3; ectopic KCTD5 expression increases RhoGDI1 ubiquitination, whereas KCTD5 knockdown stabilizes RhoGDI1 and reduces its ubiquitination, establishing CUL3/KCTD5 as an E3 ligase complex that targets RhoGDI1 for degradation.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, RNA interference knockdown, dominant-negative CUL3 expression, stability assays\",\n      \"journal\": \"Journal of microbiology and biotechnology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, and KD/DN rescue in single lab with multiple methods\",\n      \"pmids\": [\"32876072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CRISPR/Cas9 and shRNA depletion of KCTD5 in B16-F10 cells increases cell migration, cell spreading, and focal adhesion disassembly rate. These effects are mediated through Rac1 GTPase activity (dominant-negative Rac1 rescues spreading) and Ca2+ signaling (KCTD5 loss decreases serum-induced Ca2+ response; ionomycin reversal restores focal adhesion size).\",\n      \"method\": \"CRISPR/Cas9 knockout, shRNA knockdown, live-cell imaging, dominant-negative Rac1 expression, Ca2+ imaging, focal adhesion dynamics assays\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic KO with multiple orthogonal functional assays and dominant-negative rescue, single lab\",\n      \"pmids\": [\"33053687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"KCTD5 itself is ubiquitinated and degraded by the proteasome in AGS gastric epithelial cells; H. pylori infection impairs KCTD5 ubiquitination, reducing KCTD5 levels. Decreased KCTD5 (an adaptor of Cullin-3) increases H. pylori adherence, indicating KCTD5 proteasomal turnover is exploited by the pathogen to facilitate colonization.\",\n      \"method\": \"Ubiquitination assays, proteasome inhibitor experiments, H. pylori infection assays, RNA interference knockdown, adherence assays\",\n      \"journal\": \"Frontiers in cellular and infection microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ubiquitination assays and KD with specific adherence phenotype, single lab, multiple methods\",\n      \"pmids\": [\"29114497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"KCTD5 forms hetero-oligomeric complexes with numerous other KCTD family members (including KCTD2, KCTD17, and others); different regions of KCTD5 contribute distinctly to interactions with different KCTD partners.\",\n      \"method\": \"Co-immunoprecipitation, BRET (bioluminescence resonance energy transfer) in live cells, IP-luminescence domain-mapping assays\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP corroborated by live-cell BRET, single lab, two orthogonal methods\",\n      \"pmids\": [\"37762619\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"KCTD5 is identified as a key stabilizing factor for Ikaros transcription factor; etoposide treatment decreases the KCTD5-Ikaros interaction, leading to accelerated Ikaros protein degradation (affecting IK1, IK2, IK4 isoforms but not IK6/IK7) in leukemic cells.\",\n      \"method\": \"Immunoprecipitation coupled with LC-MS/MS, co-immunoprecipitation, protein stability/degradation assays, etoposide treatment experiments\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — IP/MS discovery followed by Co-IP validation and stability assays, single lab, two orthogonal methods\",\n      \"pmids\": [\"38424700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Conditional knockout of Kctd5 in striatal neurons in mice leads to dystonic phenotype, coordination deficits, and augmented electrically evoked cAMP responses to dopaminergic stimulation. Rescue by a Gβγ-scavenging nanobody confirms KCTD5 acts as a brake on Gβγ-mediated cAMP signaling in striatal circuits, and motor deficits are partially rescued by pharmacological antagonism of the indirect striatal cAMP pathway.\",\n      \"method\": \"Conditional knockout mouse (Cre-lox), 2-photon cAMP biosensor imaging, Gβγ-scavenging nanobody rescue, pharmacological rescue, behavioral assays\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional KO with in vivo imaging, nanobody rescue, and pharmacological rescue across multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"40233107\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"Heterozygous Kctd5 knockout mice (Kctd5-/- embryos are lethal in early embryonic development) exhibit abnormal lipid metabolism including elevated cholesterol and triglycerides; genome-wide expression analysis suggests KCTD5 affects the PPAR signaling pathway and expression of Apolipoprotein family genes to regulate lipid metabolism.\",\n      \"method\": \"CRISPR/Cas9 heterozygous knockout mice, metabolic profiling, genome-wide gene expression analysis\",\n      \"journal\": \"The international journal of biochemistry & cell biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — KO phenotype with transcriptomic pathway inference but no direct mechanistic validation of PPAR/Apo pathway regulation\",\n      \"pmids\": [\"40846050\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"KCTD5 acts as a positive regulator of TRPM4 channel activity, increasing Ca2+ sensitivity; peptides designed to disrupt the TRPM4-KCTD5 protein-protein interface reduce TRPM4-dependent Na+ influx and currents and decrease cell invasion in MDA-MB-231 cells, confirming the functional importance of this interaction.\",\n      \"method\": \"BiFC (bimolecular fluorescent complementation), patch clamp electrophysiology, intracellular Na+ recordings, CRISPR KCTD5 knockout cells (HEK293KCTD5-/-), cell invasion assays\",\n      \"journal\": \"Journal of chemical information and modeling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — BiFC interaction assay corroborated by electrophysiology and KO cells with multiple functional readouts, single lab\",\n      \"pmids\": [\"42214084\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KCTD5 is a pentameric BTB-domain protein that functions as a substrate-specific adaptor for Cullin3-RING E3 ubiquitin ligase complexes (CRL3KCTD5), recruiting substrates including Gβγ subunits (triggering their ubiquitination and degradation via an ARIH1 E3-E3 superassembly), RhoGDI1, ΔNp63α (monoubiquitination), and Ikaros (stabilization), thereby acting as a molecular brake on Gβγ-mediated cAMP signaling in striatal neurons important for motor coordination, while also regulating cell migration through modulation of Rac1 activity, focal adhesion dynamics, and Ca2+ signaling via TRPM4.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KCTD5 is a pentameric BTB-domain protein that serves as a substrate-specific adaptor for Cullin3-RING E3 ubiquitin ligase complexes, coupling substrate recognition to ubiquitin transfer [#0, #1]. It oligomerizes through its BTB domain and engages Cullin3 via the BTB plus additional N-terminal residues, while its C-terminal domain captures substrate [#0, #1]. Its best-characterized substrate is the heterotrimeric G protein Gβγ dimer: cryo-EM of the symmetric 5:5:5 KCTD5/CUL3/Gβγ assembly shows five Gβγ engaged simultaneously, and CRL3KCTD5 recruits the RING-between-RING ligase ARIH1 in an E3-E3 superassembly that primes ubiquitin transfer onto Gβ, thereby negatively regulating cAMP signaling downstream of GPCRs [#1, #2]. In vivo, conditional deletion of Kctd5 in striatal neurons produces a dystonic, motor-incoordinate phenotype with augmented dopaminergic cAMP responses that is rescued by a Gβγ-scavenging nanobody, establishing KCTD5 as a physiological brake on Gβγ-mediated cAMP signaling in striatal circuits [#11]. Beyond Gβγ, KCTD5/CUL3 acts on additional substrates with distinct outcomes: degradative ubiquitination of RhoGDI1 [#6], monoubiquitination of ΔNp63α that reduces its DNA binding and proliferative activity [#5], and stabilization rather than degradation of partners including ZNF711 and the Ikaros transcription factor [#3, #10]. KCTD5 also regulates the actin cytoskeleton and cell migration through Rac1 activity, focal adhesion dynamics, and Ca2+ signaling [#7], and positively regulates TRPM4 channel Ca2+ sensitivity through a defined protein-protein interface that promotes cell invasion [#13]. It forms hetero-oligomers with other KCTD family members, and its own levels are controlled by proteasomal turnover [#8, #9].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established the founding hypothesis that KCTD5 is a Cullin3 substrate adaptor rather than a passive BTB protein, defining the structural determinants of the interaction.\",\n      \"evidence\": \"Co-IP, binding assays, and BTB/N-terminal mutagenesis in cultured cells\",\n      \"pmids\": [\"18573101\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No substrate identified at this stage\", \"Ubiquitination activity not directly demonstrated\", \"Single-lab reciprocal Co-IP\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed that not all KCTD5/Cullin3 partners are degraded, revealing a non-degradative, stabilizing mode of action for some substrates.\",\n      \"evidence\": \"Yeast two-hybrid, Co-IP, and proteasome inhibitor/overexpression assays identifying MCM7, ZNF711, FAM193B\",\n      \"pmids\": [\"26188516\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism of stabilization not defined\", \"Physiological relevance of these partners unclear\", \"No ubiquitination observed despite complex formation\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Proposed how the pentameric assembly could position substrates by modeling interdomain motion, framing a structural basis for catalysis.\",\n      \"evidence\": \"120 ns molecular dynamics simulation of full-length KCTD5 pentamer identifying Ser150 hinge\",\n      \"pmids\": [\"26336981\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Computational only; Ser150 role not experimentally validated\", \"No substrate present in simulation\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrated that KCTD5 levels are themselves regulated by ubiquitin-proteasome turnover and that a pathogen exploits this to aid colonization.\",\n      \"evidence\": \"Ubiquitination/proteasome inhibitor assays, knockdown, and H. pylori adherence assays in gastric epithelial cells\",\n      \"pmids\": [\"29114497\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E3 ligase responsible for KCTD5 turnover not identified\", \"Mechanism linking KCTD5 loss to adherence not resolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Identified ΔNp63α as a substrate and showed KCTD5 imposes a regulatory monoubiquitination that tunes transcription factor activity rather than destroying it.\",\n      \"evidence\": \"Co-IP, ubiquitination, DNA-binding, transactivation reporter, and proliferation assays\",\n      \"pmids\": [\"29782646\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Monoubiquitination site not mapped\", \"Single-lab functional readouts\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Expanded the degradative substrate set to RhoGDI1 and connected KCTD5 to cytoskeletal regulation via Rac1 and Ca2+ signaling in migration.\",\n      \"evidence\": \"Co-IP, ubiquitination, KD/dominant-negative rescue, and CRISPR KO with live-cell imaging and Ca2+ imaging\",\n      \"pmids\": [\"32876072\", \"33053687\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct link between RhoGDI1 degradation and the migration phenotype not fully established\", \"Mechanism of KCTD5 effect on Ca2+ entry undefined\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Resolved the central mechanistic question of how KCTD5 acts catalytically, showing a pentameric CRL3KCTD5 engages five Gβγ symmetrically to ubiquitinate them and suppress cAMP signaling.\",\n      \"evidence\": \"Cryo-EM structure with ubiquitination and cAMP signaling assays\",\n      \"pmids\": [\"37450587\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo physiological role not yet tested at this stage\", \"How E2 delivery is coordinated across five sites not detailed\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Demonstrated KCTD5 forms hetero-oligomers with other KCTD family members, implying combinatorial adaptor assemblies.\",\n      \"evidence\": \"Co-IP, live-cell BRET, and IP-luminescence domain mapping\",\n      \"pmids\": [\"37762619\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional consequence of heteromerization for substrate selection unknown\", \"Stoichiometry of mixed oligomers not defined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined the catalytic geometry by showing CRL3KCTD5 recruits ARIH1 in an E3-E3 superassembly that positions the ubiquitin thioester near Gβ Lys-23, explaining priming of transfer.\",\n      \"evidence\": \"Cryo-EM of the dynamic 5:5:5 assembly with ubiquitylation assays and modeling of CUL3/RBX1/ARIH1~ubiquitin\",\n      \"pmids\": [\"38625940\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Processivity and chain-type specificity not fully resolved\", \"Role of >60° interdomain dynamics in turnover not directly tested\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Established a stabilizing role in leukemic cells by identifying KCTD5 as a factor that protects Ikaros isoforms from degradation under genotoxic stress.\",\n      \"evidence\": \"IP-LC-MS/MS, Co-IP, and protein stability assays with etoposide treatment\",\n      \"pmids\": [\"38424700\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of stabilization versus degradation choice unresolved\", \"Isoform selectivity mechanism unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Provided in vivo validation that KCTD5 is a physiological brake on Gβγ-mediated cAMP signaling required for motor coordination.\",\n      \"evidence\": \"Striatal conditional KO mice with 2-photon cAMP imaging, Gβγ-scavenging nanobody rescue, pharmacological rescue, and behavior\",\n      \"pmids\": [\"40233107\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type-specific substrate scope in vivo beyond Gβγ untested\", \"Link to dystonia mechanism only partially defined\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Indicated a developmental and metabolic role, with embryonic lethality of full knockout and lipid-metabolism abnormalities in heterozygotes.\",\n      \"evidence\": \"CRISPR heterozygous KO mice, metabolic profiling, genome-wide expression analysis\",\n      \"pmids\": [\"40846050\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"PPAR/Apolipoprotein pathway link is transcriptomic inference without mechanistic validation\", \"Direct substrate driving the lipid phenotype not identified\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Showed KCTD5 acts as a positive regulator of an ion channel, increasing TRPM4 Ca2+ sensitivity through a definable interface that promotes invasion.\",\n      \"evidence\": \"BiFC, patch clamp, intracellular Na+ recordings, CRISPR KO cells, interface-disrupting peptides, and invasion assays\",\n      \"pmids\": [\"42214084\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether regulation is ubiquitination-dependent unclear\", \"Structural basis of the TRPM4-KCTD5 interface not solved\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How KCTD5 chooses between degradative polyubiquitination, regulatory monoubiquitination, substrate stabilization, and ubiquitination-independent channel modulation across its diverse partners remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unifying rule distinguishes degraded versus stabilized substrates\", \"Contribution of KCTD heteromerization to substrate choice unknown\", \"Tissue-specific substrate repertoire largely uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 2, 5, 6]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [1, 2, 6]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [11, 13]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [1, 2, 6]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 11]}\n    ],\n    \"complexes\": [\n      \"CRL3KCTD5 (Cullin3-RING E3 ligase)\",\n      \"CRL3KCTD5-ARIH1 E3-E3 superassembly\"\n    ],\n    \"partners\": [\n      \"CUL3\",\n      \"ARIH1\",\n      \"GNB1\",\n      \"ARHGDIA\",\n      \"TP63\",\n      \"IKZF1\",\n      \"TRPM4\",\n      \"KCTD17\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}