{"gene":"KLHL20","run_date":"2026-06-10T02:59:49","timeline":{"discoveries":[{"year":2003,"finding":"KLEIP (KLHL20) is an actin-binding protein that localizes transiently to cell-cell contact sites during induction of cell-cell contact (not at mature junctions), colocalizing with F-actin. Constitutively active Rac1 enhanced KLEIP and F-actin recruitment to adhesion sites, while the N-terminal half of KLEIP (lacking the actin-binding site) inhibited Rac1-induced actin assembly at contact sites, indicating KLEIP participates in Rac1-induced actin organization.","method":"Co-localization microscopy, E-cadherin-bead recruitment assay, cytochalasin B treatment, constitutively active Rac1 overexpression, dominant-negative fragment expression in MDCK cells","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiments with functional consequence, multiple complementary approaches in single lab","pmids":["14668487"],"is_preprint":false},{"year":2007,"finding":"KLEIP (KLHL20) acts as an essential downstream regulator of VEGF- and bFGF-induced endothelial cell migration and sprouting angiogenesis. KLEIP depletion blunted VEGF-induced RhoA activation (but not ERK1/2 activation), and VEGF induced physical association of KLEIP with the guanine nucleotide exchange factor ECT2.","method":"siRNA knockdown in endothelial cells, in-gel sprouting angiogenesis assay, RhoA and ERK1/2 activation assays, co-immunoprecipitation of KLEIP with ECT2","journal":"Circulation research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KD with defined cellular phenotype plus Co-IP showing KLEIP-ECT2 interaction, single lab","pmids":["17395875"],"is_preprint":false},{"year":2010,"finding":"KLHL20 forms a Cul3-ROC1 E3 ligase complex (via its BTB domain binding Cul3 and Kelch-repeat domain binding DAPK) that promotes DAPK polyubiquitination and proteasomal degradation. IFN-alpha/gamma induces sequestration of KLHL20 in PML nuclear bodies, separating it from DAPK and thereby stabilizing DAPK to enable IFN-induced apoptosis and autophagy.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA depletion of KLHL20, domain-mapping experiments (Kelch vs. BTB), immunofluorescence showing KLHL20 redistribution to PML nuclear bodies upon IFN treatment","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, ubiquitination assay, domain mapping, siRNA rescue, and subcellular localization with functional consequence all in one study","pmids":["20389280"],"is_preprint":false},{"year":2011,"finding":"KLHL20 functions as a Cul3 substrate adaptor that targets PML for proteasomal degradation through a pathway requiring CDK1/2-mediated and Pin1-mediated modifications of PML. This KLHL20-mediated PML destruction acts in a positive feedback loop to maximize HIF-1α induction under hypoxia, potentiating tumor hypoxia responses including metabolic reprogramming, EMT, migration, angiogenesis, and chemoresistance. KLHL20 expression is itself induced by HIF-1.","method":"Co-immunoprecipitation, ubiquitination assays, siRNA knockdown, dominant-negative constructs, in vivo tumor xenograft models, epistasis experiments placing CDK1/2 and Pin1 upstream of KLHL20-mediated PML degradation","journal":"Cancer cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (Co-IP, ubiquitination assay, genetic epistasis, in vivo models) in a single rigorous study","pmids":["21840486"],"is_preprint":false},{"year":2011,"finding":"The Cul3-KLHL20 ubiquitin ligase complex targets PDZ-RhoGEF for ubiquitin-dependent proteolysis, restricting RhoA activity and facilitating growth cone spreading and neurite outgrowth. PDZ-RhoGEF phosphorylation by p38 MAPK is required for its recruitment to KLHL20, and neurotrophins (BDNF, NT-3) activate p38 to potentiate this degradation pathway.","method":"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, primary hippocampal/cortical neuron culture, neurite outgrowth/arborization measurements, p38 inhibition and phosphorylation analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, ubiquitination assay, KD with defined neuronal phenotype, pathway placement via kinase epistasis in single rigorous study","pmids":["21670212"],"is_preprint":false},{"year":2014,"finding":"KLHL20 localizes to the trans-Golgi network (TGN) and promotes post-Golgi trafficking by catalyzing K33-linked (non-degradative) polyubiquitination of coronin 7 (Crn7) via the Cul3-KLHL20 E3 ligase. K33-ubiquitinated Crn7 is targeted to the TGN through a ubiquitin-dependent interaction with Eps15, where it promotes TGN-pool F-actin assembly required for transport carrier biogenesis.","method":"Co-immunoprecipitation, in vitro ubiquitination assay with linkage-specific analysis, siRNA knockdown, subcellular fractionation/immunofluorescence, dominant-negative ubiquitin mutants (K33R), enforced Crn7 TGN targeting as epistasis","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro ubiquitination assay, linkage-specific ubiquitin mutants, Co-IP, subcellular localization with functional consequence, genetic epistasis, multiple orthogonal methods","pmids":["24768539"],"is_preprint":false},{"year":2015,"finding":"KLHL39, another BTB-Kelch protein, acts as a negative regulator of Cul3-KLHL20 E3 ligase by binding to the substrate-binding (Kelch) domain of KLHL20, thereby disrupting both substrate (PML, DAPK) binding to KLHL20 and KLHL20 binding to Cul3. This dual blockade increases PML and DAPK stability. KLHL39 itself lacks Cul3-binding ability due to absent conserved BTB-domain residues and is not a KLHL20 substrate.","method":"Co-immunoprecipitation, domain-mapping, ubiquitination assays, siRNA knockdown, in vitro migration/invasion assays, in vivo metastasis model","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, domain mapping, ubiquitination assays, and functional rescue in single rigorous study with multiple substrates","pmids":["25619834"],"is_preprint":false},{"year":2015,"finding":"Cul3-KLHL20 E3 ligase ubiquitinates ULK1 (an autophagy-initiating kinase) to promote its proteasomal degradation. ULK1 autophosphorylation upon autophagy induction facilitates its recruitment to KLHL20. KLHL20 also governs degradation of ATG13, VPS34, Beclin-1, and ATG14 during prolonged starvation (directly or indirectly), thereby terminating autophagy. Impairment of this pathway potentiates starvation-induced cell death and aggravates diabetes-associated muscle atrophy.","method":"Co-immunoprecipitation, ubiquitination assays, siRNA/shRNA knockdown and knockout mouse models, in vitro kinase assays, autophagic flux assays, diabetes mouse model","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — in vitro ubiquitination, Co-IP, KO mouse model with physiological phenotype, multiple orthogonal methods demonstrating pathway","pmids":["26687681"],"is_preprint":false},{"year":2014,"finding":"KLEIP (KLHL20) regulates HIF-2α stabilization and transcriptional activation in lung endothelial cells. KLEIP knockout mice show strongly reduced Hif-2α and VEGF mRNA/protein levels in embryonic lungs, associated with endothelial apoptosis; betamethasone treatment rescues this by increasing Hif-2α expression. KLEIP expression is controlled by two hypoxia response elements.","method":"KLEIP knockout mouse generation, immunohistochemistry, Western blotting, mRNA expression analysis, betamethasone rescue experiment","journal":"Disease models & mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse with defined phenotype and pathway placement, single lab","pmids":["24785085"],"is_preprint":false},{"year":2019,"finding":"Crystal structure (1.1 Å) of the KLHL20 Kelch domain bound to a DAPK1 death-domain peptide reveals that DAPK1 binds via an 'LPDLV' motif as a loose helical turn inserting deeply into the central pocket of the β-propeller to contact all six blades. KLHL20 engages DAPK1 through salt-bridge and hydrophobic interactions involving tryptophan and cysteine residues.","method":"X-ray crystallography at 1.1 Å resolution, peptide binding assays, mutagenesis to identify critical residues","journal":"Structure","confidence":"High","confidence_rationale":"Tier 1 / Strong — high-resolution crystal structure with mutagenesis validation identifying the binding motif","pmids":["31279627"],"is_preprint":false},{"year":2022,"finding":"Cul3-KLHL20 (localized at the TGN) polyubiquitinates SERINC5 at lysine 130 via K33/K48-linked chains. K33-linked polyubiquitination determines SERINC5 expression on the plasma membrane (post-Golgi trafficking), while K48-linked polyubiquitination contributes to SERINC5 downregulation/degradation from the cell surface. HIV-1 Nef counteracts SERINC5 restriction independently of this pathway.","method":"Co-immunoprecipitation, ubiquitination assay with linkage-specific analysis, site-directed mutagenesis (K130R SERINC5), flow cytometry, siRNA knockdown","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — ubiquitination assay, linkage-specific mutants, site-directed mutagenesis, Co-IP, flow cytometry, multiple orthogonal methods in single study","pmids":["35474067"],"is_preprint":false},{"year":2022,"finding":"De novo missense variants in KLHL20 cause a neurodevelopmental syndrome. All 14 patient variants clustered in the Kelch-type β-propeller domain (substrate-binding surface), with a recurrent variant Gly357Arg found in 11 patients, suggesting that disruption of substrate recognition by KLHL20 underlies this disorder.","method":"Patient cohort genotyping via Matchmaker Exchange, variant mapping onto known KLHL20 domain structure","journal":"Genetics in medicine","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — genetic mapping of disease-causing variants to functional domain, no direct functional assay per abstract, but replicated across 14 patients","pmids":["36214804"],"is_preprint":false},{"year":2023,"finding":"p53 upregulates KLHL20 expression, and the resulting CUL3-KLHL20 E3 ligase complex mediates proteasomal degradation of ZBTB7A. HSP90 inhibition (by 17-AAG) triggers p53-dependent upregulation of KLHL20, leading to ZBTB7A proteolysis and derepression of p21/CDKN1A.","method":"Co-immunoprecipitation, protein stability assays, siRNA knockdown, HSP90 inhibitor treatment, Western blotting","journal":"Biochimica et biophysica acta. Gene regulatory mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, knockdown, protein stability assays; single lab, multiple methods","pmids":["37011832"],"is_preprint":false},{"year":2026,"finding":"KLHL20 interacts with ZFTA (zinc finger translocation associated protein) via its Kelch domain with an estimated KD ~35 µM, exhibiting 'fuzzy binding' through feature-specific rather than sequence-specific recognition. The interaction specificity for KLHL20 vs. KLHL12 was confirmed. This mechanism reflects KLHL20's role as an adaptor for disordered substrate recognition.","method":"Biosensor (SPR/BLI) analysis, AlphaFold2-based structural modeling, truncation peptide binding experiments","journal":"Chembiochem","confidence":"Low","confidence_rationale":"Tier 3 / Weak — biosensor analysis with computational modeling, single study, no in-cell ubiquitination confirmation reported in abstract","pmids":["41762441"],"is_preprint":false},{"year":2026,"finding":"Under high glucose conditions, KLHL20 expression is transcriptionally suppressed, leading to reduced DAPK1 ubiquitination and elevated DAPK1 protein levels that promote mitochondrial apoptosis in renal tubular cells. KLHL20 overexpression restores DAPK1 ubiquitination and reduces protein levels (without affecting mRNA), confirming KLHL20 as an E3 adaptor for DAPK1 post-translational regulation in this context.","method":"Co-immunoprecipitation, ubiquitination assay, KLHL20 overexpression, DAPK1 knockdown, protein stability/half-life assay, db/db mouse model, HK-2 cell model","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP, ubiquitination assay, OE/KD with functional rescue, in vivo model; single lab","pmids":["41637987"],"is_preprint":false}],"current_model":"KLHL20 is a BTB-Kelch domain protein that functions as the substrate-adaptor subunit of a CUL3-ROC1 RING E3 ubiquitin ligase complex, recognizing substrates (DAPK1, PML, ULK1, VPS34/Beclin-1/ATG14, PDZ-RhoGEF, coronin 7, SERINC5, ZBTB7A) via its Kelch β-propeller domain and directing either degradative (K48-linked) or non-degradative (K33-linked) polyubiquitination; its subcellular localization (cytoplasm, TGN, or PML nuclear bodies) is dynamically regulated by stress signals (IFN, hypoxia, autophagy induction) to switch substrate targeting, thereby controlling autophagy termination, post-Golgi vesicle trafficking, RhoA-dependent neurite outgrowth, HIF-1α amplification in hypoxia, and IFN-induced DAPK-mediated cell death."},"narrative":{"mechanistic_narrative":"KLHL20 is a BTB-Kelch protein that functions as the substrate-recognition subunit of a CUL3-ROC1 RING E3 ubiquitin ligase, in which its BTB domain engages Cul3 and its Kelch β-propeller domain captures substrates [PMID:20389280]. A high-resolution structure of the Kelch domain bound to a DAPK1 death-domain peptide shows substrates insert an 'LPDLV' motif deep into the central pocket of the β-propeller to contact all six blades [PMID:31279627], and KLHL20 directs both degradative (K48-linked) and non-degradative (K33-linked) polyubiquitination depending on substrate and signal [PMID:24768539, PMID:35474067]. Through this activity KLHL20 controls multiple cellular programs: it terminates autophagy by ubiquitinating the autophagy-initiating kinase ULK1 and governing turnover of VPS34, Beclin-1, ATG13 and ATG14 during prolonged starvation [PMID:26687681]; it promotes post-Golgi vesicle trafficking from the trans-Golgi network by K33-linked ubiquitination of coronin 7, routing it via Eps15 to drive TGN F-actin assembly [PMID:24768539]; and it restrains RhoA-dependent neurite outgrowth by degrading p38-phosphorylated PDZ-RhoGEF [PMID:21670212]. KLHL20 activity is regulated at the level of localization and signaling: IFN-α/γ sequesters KLHL20 in PML nuclear bodies to stabilize DAPK and license IFN-induced apoptosis and autophagy [PMID:20389280], while under hypoxia KLHL20 degrades PML in a CDK1/2- and Pin1-dependent feedback loop that amplifies HIF-1α and tumor hypoxia responses [PMID:21840486]. Its substrate repertoire extends to SERINC5 (controlling plasma-membrane delivery versus degradation) [PMID:35474067] and the transcriptional repressor ZBTB7A in a p53-induced axis that derepresses p21 [PMID:37011832]. KLHL39, a related BTB-Kelch protein lacking Cul3-binding residues, antagonizes the ligase by occupying the Kelch domain and blocking both substrate and Cul3 engagement [PMID:25619834]. De novo missense variants clustering in the substrate-binding β-propeller surface, including a recurrent Gly357Arg, cause a neurodevelopmental syndrome [PMID:36214804].","teleology":[{"year":2003,"claim":"Before any enzymatic role was known, KLHL20 was placed in actin cytoskeletal dynamics, establishing an early link to Rac1-driven actin organization at nascent cell-cell contacts.","evidence":"Co-localization microscopy, E-cadherin-bead recruitment, and dominant-negative fragment expression in MDCK cells","pmids":["14668487"],"confidence":"Medium","gaps":["No molecular activity or E3 ligase role identified at this stage","Mechanism connecting actin binding to later ubiquitin ligase function not defined"]},{"year":2007,"claim":"KLHL20 was tied to RhoA signaling in endothelial migration, showing it acts upstream of RhoA activation and physically associates with the GEF ECT2 during angiogenic responses.","evidence":"siRNA knockdown, sprouting angiogenesis assay, RhoA activation assays, and Co-IP of KLHL20 with ECT2 in endothelial cells","pmids":["17395875"],"confidence":"Medium","gaps":["Whether KLHL20-ECT2 interaction is ubiquitination-dependent unresolved","Single lab, single Co-IP for the interaction"]},{"year":2010,"claim":"The defining mechanistic advance: KLHL20 was shown to be a CUL3-ROC1 substrate adaptor that degrades DAPK, and stress-induced sequestration in PML bodies emerged as a localization switch controlling substrate access.","evidence":"Reciprocal Co-IP, ubiquitination assay, BTB/Kelch domain mapping, siRNA, and IFN-induced relocalization to PML nuclear bodies","pmids":["20389280"],"confidence":"High","gaps":["Structural basis of DAPK recognition not yet resolved","Generality of PML sequestration to other substrates unknown"]},{"year":2011,"claim":"KLHL20 was connected to hypoxia and neuronal morphogenesis by identifying PML and PDZ-RhoGEF as substrates, revealing kinase-gated substrate recruitment (CDK1/2-Pin1 and p38) and a HIF-1α amplification feedback loop.","evidence":"Co-IP, ubiquitination assays, genetic epistasis, xenograft and primary neuron models with kinase inhibition","pmids":["21840486","21670212"],"confidence":"High","gaps":["How a single adaptor coordinates context-specific substrate selection unresolved","Direct versus indirect degradation of some downstream factors not fully separated"]},{"year":2014,"claim":"KLHL20 was assigned a non-degradative ubiquitin function and a TGN localization, demonstrating K33-linked ubiquitination of coronin 7 to drive post-Golgi carrier biogenesis, broadening its output beyond proteolysis.","evidence":"In vitro linkage-specific ubiquitination, K33R ubiquitin mutants, Co-IP, subcellular fractionation, and enforced-targeting epistasis","pmids":["24768539"],"confidence":"High","gaps":["How KLHL20 selects K33 versus K48 linkage at the molecular level unknown","Determinants of TGN recruitment of KLHL20 itself not defined"]},{"year":2014,"claim":"A KLHL20 knockout mouse linked it to HIF-2α stabilization and VEGF expression in lung endothelium, reinforcing a hypoxia-signaling role in vivo.","evidence":"KLEIP knockout mice, immunohistochemistry, expression analysis, and betamethasone rescue","pmids":["24785085"],"confidence":"Medium","gaps":["Direct ubiquitin-mediated mechanism on HIF-2α not established","Relationship to the PML/HIF-1α feedback loop unclear"]},{"year":2015,"claim":"KLHL20 was established as the terminator of autophagy via ULK1 ubiquitination and turnover of multiple autophagy regulators, and a negative regulator (KLHL39) was identified that blocks the ligase by occupying its Kelch domain.","evidence":"Co-IP, ubiquitination assays, knockout mouse and diabetes models, in vitro kinase assays (ULK1); domain-mapping and rescue (KLHL39)","pmids":["26687681","25619834"],"confidence":"High","gaps":["Which autophagy substrates are direct versus indirect not fully resolved","Physiological signals controlling KLHL39 expression unknown"]},{"year":2019,"claim":"A 1.1 Å crystal structure of the Kelch domain with a DAPK1 peptide defined the substrate-recognition mechanism, showing the LPDLV motif buried in the β-propeller central pocket.","evidence":"X-ray crystallography with peptide binding and mutagenesis","pmids":["31279627"],"confidence":"High","gaps":["Whether all substrates share an LPDLV-like motif not established","Structure of the full CUL3-bound complex absent"]},{"year":2022,"claim":"Substrate scope and disease relevance expanded: KLHL20 was shown to dual-ubiquitinate SERINC5 to balance surface delivery versus degradation, and de novo Kelch-domain variants were linked to a neurodevelopmental syndrome.","evidence":"Linkage-specific ubiquitination and flow cytometry (SERINC5); patient cohort genotyping and variant mapping (neurodevelopmental syndrome)","pmids":["35474067","36214804"],"confidence":"Medium","gaps":["No direct functional assay of patient variants reported","Which neuronal substrates underlie the disorder unidentified"]},{"year":2023,"claim":"KLHL20 was placed downstream of p53, mediating ZBTB7A degradation upon HSP90 inhibition and thereby derepressing p21, extending its reach into transcriptional and cell-cycle control.","evidence":"Co-IP, protein stability assays, siRNA, and HSP90 inhibitor treatment","pmids":["37011832"],"confidence":"Medium","gaps":["Single lab; ubiquitination linkage on ZBTB7A not characterized","Direct versus indirect p21 derepression not separated"]},{"year":2026,"claim":"Disease-context regulation and a 'fuzzy' substrate-binding mode were probed: high-glucose suppression of KLHL20 elevates DAPK1 to drive renal tubular apoptosis, and biosensor/computational work characterized low-affinity feature-specific recognition of ZFTA.","evidence":"Co-IP, ubiquitination and half-life assays with db/db and HK-2 models (DAPK1); SPR/BLI and AlphaFold2 modeling (ZFTA)","pmids":["41637987","41762441"],"confidence":"Medium","gaps":["ZFTA finding is Low confidence with no in-cell ubiquitination confirmation","How fuzzy binding reconciles with the defined LPDLV pocket mode unclear"]},{"year":null,"claim":"It remains unresolved how a single Kelch adaptor achieves context-dependent selection among its many substrates and how the choice between K33- and K48-linked chains is mechanistically encoded.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model for linkage-type determination","No structure of the assembled CUL3-KLHL20 complex with substrate","Patient variant consequences not functionally tested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,3,4,5,7,10]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[2,5,7,10]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,9,13]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[5,10]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[2]}],"pathway":[{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[7]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[2,3,4,5,7,10]},{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[5,10]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[2,14]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[2,3,7]}],"complexes":["CUL3-ROC1 (Cullin-RING) E3 ubiquitin ligase"],"partners":["CUL3","DAPK1","PML","ULK1","PDZ-RHOGEF (ARHGEF11)","SERINC5","KLHL39","ECT2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9Y2M5","full_name":"Kelch-like protein 20","aliases":["Kelch-like ECT2-interacting protein","Kelch-like protein X"],"length_aa":609,"mass_kda":68.0,"function":"Substrate-specific adapter of a BCR (BTB-CUL3-RBX1) E3 ubiquitin-protein ligase complex involved in interferon response and anterograde Golgi to endosome transport. The BCR(KLHL20) E3 ubiquitin ligase complex mediates the ubiquitination of DAPK1, leading to its degradation by the proteasome, thereby acting as a negative regulator of apoptosis (PubMed:20389280). The BCR(KLHL20) E3 ubiquitin ligase complex also specifically mediates 'Lys-33'-linked ubiquitination (PubMed:24768539). Involved in anterograde Golgi to endosome transport by mediating 'Lys-33'-linked ubiquitination of CORO7, promoting interaction between CORO7 and EPS15, thereby facilitating actin polymerization and post-Golgi trafficking (PubMed:24768539). Also acts as a regulator of endothelial migration during angiogenesis by controlling the activation of Rho GTPases. The BCR(KLHL20) E3 ubiquitin ligase complex acts as a regulator of neurite outgrowth by mediating ubiquitination and degradation of PDZ-RhoGEF/ARHGEF11 (PubMed:21670212). In case of tumor, the BCR(KLHL20) E3 ubiquitin ligase complex is involved in tumor hypoxia: following hypoxia, the BCR(KLHL20)complex mediates ubiquitination and degradation of PML, potentiating HIF-1 signaling and cancer progression (PubMed:21840486)","subcellular_location":"Cytoplasm, perinuclear region; Nucleus; Golgi apparatus, trans-Golgi network; Cell projection, axon; Cell projection, dendrite","url":"https://www.uniprot.org/uniprotkb/Q9Y2M5/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KLHL20","classification":"Not Classified","n_dependent_lines":5,"n_total_lines":1208,"dependency_fraction":0.0041390728476821195},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CLTA","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/KLHL20","total_profiled":1310},"omim":[{"mim_id":"621390","title":"NEURODEVELOPMENTAL DISORDER WITH EARLY-ONSET SEIZURES, FACIAL DYSMORPHISM, AND BEHAVIORAL ABNORMALITIES; NEDSZFB","url":"https://www.omim.org/entry/621390"},{"mim_id":"617679","title":"KELCH-LIKE 20; KLHL20","url":"https://www.omim.org/entry/617679"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Golgi apparatus","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KLHL20"},"hgnc":{"alias_symbol":["KLEIP","KHLHX"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y2M5","domains":[{"cath_id":"3.30.710.10","chopping":"50-164","consensus_level":"high","plddt":94.4946,"start":50,"end":164},{"cath_id":"1.25.40.420","chopping":"209-301","consensus_level":"high","plddt":93.6845,"start":209,"end":301},{"cath_id":"2.120.10.80","chopping":"317-599","consensus_level":"medium","plddt":94.7751,"start":317,"end":599}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2M5","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2M5-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y2M5-F1-predicted_aligned_error_v6.png","plddt_mean":88.44},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KLHL20","jax_strain_url":"https://www.jax.org/strain/search?query=KLHL20"},"sequence":{"accession":"Q9Y2M5","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y2M5.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y2M5/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y2M5"}},"corpus_meta":[{"pmid":"26687681","id":"PMC_26687681","title":"Cul3-KLHL20 Ubiquitin Ligase Governs the Turnover of ULK1 and VPS34 Complexes to Control Autophagy Termination.","date":"2015","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/26687681","citation_count":188,"is_preprint":false},{"pmid":"21840486","id":"PMC_21840486","title":"A Cullin3-KLHL20 Ubiquitin ligase-dependent pathway targets PML to potentiate HIF-1 signaling and prostate cancer progression.","date":"2011","source":"Cancer cell","url":"https://pubmed.ncbi.nlm.nih.gov/21840486","citation_count":151,"is_preprint":false},{"pmid":"24768539","id":"PMC_24768539","title":"K33-Linked Polyubiquitination of Coronin 7 by Cul3-KLHL20 Ubiquitin E3 Ligase Regulates Protein Trafficking.","date":"2014","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/24768539","citation_count":139,"is_preprint":false},{"pmid":"20389280","id":"PMC_20389280","title":"The Cullin 3 substrate adaptor KLHL20 mediates DAPK ubiquitination to control interferon 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science","url":"https://pubmed.ncbi.nlm.nih.gov/24917145","citation_count":27,"is_preprint":false},{"pmid":"27042198","id":"PMC_27042198","title":"Cul3-KLHL20 ubiquitin ligase: physiological functions, stress responses, and disease implications.","date":"2016","source":"Cell division","url":"https://pubmed.ncbi.nlm.nih.gov/27042198","citation_count":19,"is_preprint":false},{"pmid":"36328355","id":"PMC_36328355","title":"A synthetic KLHL20 ligand to validate CUL3KLHL20 as a potent E3 ligase for targeted protein degradation.","date":"2022","source":"Genes & development","url":"https://pubmed.ncbi.nlm.nih.gov/36328355","citation_count":19,"is_preprint":false},{"pmid":"35474067","id":"PMC_35474067","title":"Cul3-KLHL20 E3 ubiquitin ligase plays a key role in the arms race between HIV-1 Nef and host SERINC5 restriction.","date":"2022","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/35474067","citation_count":17,"is_preprint":false},{"pmid":"22511632","id":"PMC_22511632","title":"KLEIP deficiency in mice causes progressive corneal neovascular dystrophy.","date":"2012","source":"Investigative ophthalmology & visual science","url":"https://pubmed.ncbi.nlm.nih.gov/22511632","citation_count":15,"is_preprint":false},{"pmid":"26985984","id":"PMC_26985984","title":"KLHL20 links the ubiquitin-proteasome system to autophagy termination.","date":"2016","source":"Autophagy","url":"https://pubmed.ncbi.nlm.nih.gov/26985984","citation_count":13,"is_preprint":false},{"pmid":"24785085","id":"PMC_24785085","title":"Kelch-like ECT2-interacting protein KLEIP regulates late-stage pulmonary maturation via Hif-2α in mice.","date":"2014","source":"Disease models & mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/24785085","citation_count":11,"is_preprint":false},{"pmid":"36214804","id":"PMC_36214804","title":"De novo missense variants in the E3 ubiquitin ligase adaptor KLHL20 cause a developmental disorder with intellectual disability, epilepsy, and autism spectrum disorder.","date":"2022","source":"Genetics in medicine : official journal of the American College of Medical Genetics","url":"https://pubmed.ncbi.nlm.nih.gov/36214804","citation_count":7,"is_preprint":false},{"pmid":"39233199","id":"PMC_39233199","title":"KLHL20 and its role in cell homeostasis: A new perspective and therapeutic potential.","date":"2024","source":"Life sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39233199","citation_count":3,"is_preprint":false},{"pmid":"37011832","id":"PMC_37011832","title":"Post-translational regulation of proto-oncogene ZBTB7A expression by p53 status in cancer cells: HSP90-dependent stabilization vs. p53-KLHL20-ubiquitin proteasomal degradation.","date":"2023","source":"Biochimica et biophysica acta. Gene regulatory mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/37011832","citation_count":3,"is_preprint":false},{"pmid":"40891966","id":"PMC_40891966","title":"Temporal and Spatial Characterization of CUL3KLHL20-Driven Targeted Degradation of BET Family BRD Proteins by the Macrocycle-Based Degrader BTR2004.","date":"2025","source":"ACS chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/40891966","citation_count":1,"is_preprint":false},{"pmid":"39677683","id":"PMC_39677683","title":"Temporal and Spatial Characterization of CUL3KLHL20-driven Targeted Degradation of BET family, BRD Proteins by the Macrocycle-based Degrader BTR2004.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/39677683","citation_count":1,"is_preprint":false},{"pmid":"41762441","id":"PMC_41762441","title":"Identification of ZFTA as a Novel KLHL20 Substrate and Mechanistic Insights Into Fuzzy Binding of Disordered Peptides via Biosensor Analysis and Computational Modelling.","date":"2026","source":"Chembiochem : a European journal of chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/41762441","citation_count":0,"is_preprint":false},{"pmid":"41637987","id":"PMC_41637987","title":"KLHL20 alleviates high glucose-induced mitochondrial apoptosis in renal tubular cells by targeting DAPK1 for ubiquitination and degradation.","date":"2026","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/41637987","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2024.12.07.627262","title":"Temporal and Spatial Characterization of CUL3  <sup>KLHL20</sup>  -driven Targeted Degradation of BET family, BRD Proteins by the Macrocycle-based Degrader BTR2004","date":"2024-12-07","source":"bioRxiv","url":"https://doi.org/10.1101/2024.12.07.627262","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13320,"output_tokens":4409,"usd":0.053047,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12368,"output_tokens":4506,"usd":0.087245,"stage2_stop_reason":"end_turn"},"total_usd":0.140292,"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\": 2003,\n      \"finding\": \"KLEIP (KLHL20) is an actin-binding protein that localizes transiently to cell-cell contact sites during induction of cell-cell contact (not at mature junctions), colocalizing with F-actin. Constitutively active Rac1 enhanced KLEIP and F-actin recruitment to adhesion sites, while the N-terminal half of KLEIP (lacking the actin-binding site) inhibited Rac1-induced actin assembly at contact sites, indicating KLEIP participates in Rac1-induced actin organization.\",\n      \"method\": \"Co-localization microscopy, E-cadherin-bead recruitment assay, cytochalasin B treatment, constitutively active Rac1 overexpression, dominant-negative fragment expression in MDCK cells\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiments with functional consequence, multiple complementary approaches in single lab\",\n      \"pmids\": [\"14668487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"KLEIP (KLHL20) acts as an essential downstream regulator of VEGF- and bFGF-induced endothelial cell migration and sprouting angiogenesis. KLEIP depletion blunted VEGF-induced RhoA activation (but not ERK1/2 activation), and VEGF induced physical association of KLEIP with the guanine nucleotide exchange factor ECT2.\",\n      \"method\": \"siRNA knockdown in endothelial cells, in-gel sprouting angiogenesis assay, RhoA and ERK1/2 activation assays, co-immunoprecipitation of KLEIP with ECT2\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KD with defined cellular phenotype plus Co-IP showing KLEIP-ECT2 interaction, single lab\",\n      \"pmids\": [\"17395875\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"KLHL20 forms a Cul3-ROC1 E3 ligase complex (via its BTB domain binding Cul3 and Kelch-repeat domain binding DAPK) that promotes DAPK polyubiquitination and proteasomal degradation. IFN-alpha/gamma induces sequestration of KLHL20 in PML nuclear bodies, separating it from DAPK and thereby stabilizing DAPK to enable IFN-induced apoptosis and autophagy.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA depletion of KLHL20, domain-mapping experiments (Kelch vs. BTB), immunofluorescence showing KLHL20 redistribution to PML nuclear bodies upon IFN treatment\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, ubiquitination assay, domain mapping, siRNA rescue, and subcellular localization with functional consequence all in one study\",\n      \"pmids\": [\"20389280\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"KLHL20 functions as a Cul3 substrate adaptor that targets PML for proteasomal degradation through a pathway requiring CDK1/2-mediated and Pin1-mediated modifications of PML. This KLHL20-mediated PML destruction acts in a positive feedback loop to maximize HIF-1α induction under hypoxia, potentiating tumor hypoxia responses including metabolic reprogramming, EMT, migration, angiogenesis, and chemoresistance. KLHL20 expression is itself induced by HIF-1.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, siRNA knockdown, dominant-negative constructs, in vivo tumor xenograft models, epistasis experiments placing CDK1/2 and Pin1 upstream of KLHL20-mediated PML degradation\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (Co-IP, ubiquitination assay, genetic epistasis, in vivo models) in a single rigorous study\",\n      \"pmids\": [\"21840486\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"The Cul3-KLHL20 ubiquitin ligase complex targets PDZ-RhoGEF for ubiquitin-dependent proteolysis, restricting RhoA activity and facilitating growth cone spreading and neurite outgrowth. PDZ-RhoGEF phosphorylation by p38 MAPK is required for its recruitment to KLHL20, and neurotrophins (BDNF, NT-3) activate p38 to potentiate this degradation pathway.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, siRNA knockdown, primary hippocampal/cortical neuron culture, neurite outgrowth/arborization measurements, p38 inhibition and phosphorylation analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, ubiquitination assay, KD with defined neuronal phenotype, pathway placement via kinase epistasis in single rigorous study\",\n      \"pmids\": [\"21670212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"KLHL20 localizes to the trans-Golgi network (TGN) and promotes post-Golgi trafficking by catalyzing K33-linked (non-degradative) polyubiquitination of coronin 7 (Crn7) via the Cul3-KLHL20 E3 ligase. K33-ubiquitinated Crn7 is targeted to the TGN through a ubiquitin-dependent interaction with Eps15, where it promotes TGN-pool F-actin assembly required for transport carrier biogenesis.\",\n      \"method\": \"Co-immunoprecipitation, in vitro ubiquitination assay with linkage-specific analysis, siRNA knockdown, subcellular fractionation/immunofluorescence, dominant-negative ubiquitin mutants (K33R), enforced Crn7 TGN targeting as epistasis\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro ubiquitination assay, linkage-specific ubiquitin mutants, Co-IP, subcellular localization with functional consequence, genetic epistasis, multiple orthogonal methods\",\n      \"pmids\": [\"24768539\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"KLHL39, another BTB-Kelch protein, acts as a negative regulator of Cul3-KLHL20 E3 ligase by binding to the substrate-binding (Kelch) domain of KLHL20, thereby disrupting both substrate (PML, DAPK) binding to KLHL20 and KLHL20 binding to Cul3. This dual blockade increases PML and DAPK stability. KLHL39 itself lacks Cul3-binding ability due to absent conserved BTB-domain residues and is not a KLHL20 substrate.\",\n      \"method\": \"Co-immunoprecipitation, domain-mapping, ubiquitination assays, siRNA knockdown, in vitro migration/invasion assays, in vivo metastasis model\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, domain mapping, ubiquitination assays, and functional rescue in single rigorous study with multiple substrates\",\n      \"pmids\": [\"25619834\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Cul3-KLHL20 E3 ligase ubiquitinates ULK1 (an autophagy-initiating kinase) to promote its proteasomal degradation. ULK1 autophosphorylation upon autophagy induction facilitates its recruitment to KLHL20. KLHL20 also governs degradation of ATG13, VPS34, Beclin-1, and ATG14 during prolonged starvation (directly or indirectly), thereby terminating autophagy. Impairment of this pathway potentiates starvation-induced cell death and aggravates diabetes-associated muscle atrophy.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, siRNA/shRNA knockdown and knockout mouse models, in vitro kinase assays, autophagic flux assays, diabetes mouse model\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — in vitro ubiquitination, Co-IP, KO mouse model with physiological phenotype, multiple orthogonal methods demonstrating pathway\",\n      \"pmids\": [\"26687681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"KLEIP (KLHL20) regulates HIF-2α stabilization and transcriptional activation in lung endothelial cells. KLEIP knockout mice show strongly reduced Hif-2α and VEGF mRNA/protein levels in embryonic lungs, associated with endothelial apoptosis; betamethasone treatment rescues this by increasing Hif-2α expression. KLEIP expression is controlled by two hypoxia response elements.\",\n      \"method\": \"KLEIP knockout mouse generation, immunohistochemistry, Western blotting, mRNA expression analysis, betamethasone rescue experiment\",\n      \"journal\": \"Disease models & mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse with defined phenotype and pathway placement, single lab\",\n      \"pmids\": [\"24785085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Crystal structure (1.1 Å) of the KLHL20 Kelch domain bound to a DAPK1 death-domain peptide reveals that DAPK1 binds via an 'LPDLV' motif as a loose helical turn inserting deeply into the central pocket of the β-propeller to contact all six blades. KLHL20 engages DAPK1 through salt-bridge and hydrophobic interactions involving tryptophan and cysteine residues.\",\n      \"method\": \"X-ray crystallography at 1.1 Å resolution, peptide binding assays, mutagenesis to identify critical residues\",\n      \"journal\": \"Structure\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — high-resolution crystal structure with mutagenesis validation identifying the binding motif\",\n      \"pmids\": [\"31279627\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Cul3-KLHL20 (localized at the TGN) polyubiquitinates SERINC5 at lysine 130 via K33/K48-linked chains. K33-linked polyubiquitination determines SERINC5 expression on the plasma membrane (post-Golgi trafficking), while K48-linked polyubiquitination contributes to SERINC5 downregulation/degradation from the cell surface. HIV-1 Nef counteracts SERINC5 restriction independently of this pathway.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay with linkage-specific analysis, site-directed mutagenesis (K130R SERINC5), flow cytometry, siRNA knockdown\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ubiquitination assay, linkage-specific mutants, site-directed mutagenesis, Co-IP, flow cytometry, multiple orthogonal methods in single study\",\n      \"pmids\": [\"35474067\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"De novo missense variants in KLHL20 cause a neurodevelopmental syndrome. All 14 patient variants clustered in the Kelch-type β-propeller domain (substrate-binding surface), with a recurrent variant Gly357Arg found in 11 patients, suggesting that disruption of substrate recognition by KLHL20 underlies this disorder.\",\n      \"method\": \"Patient cohort genotyping via Matchmaker Exchange, variant mapping onto known KLHL20 domain structure\",\n      \"journal\": \"Genetics in medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — genetic mapping of disease-causing variants to functional domain, no direct functional assay per abstract, but replicated across 14 patients\",\n      \"pmids\": [\"36214804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"p53 upregulates KLHL20 expression, and the resulting CUL3-KLHL20 E3 ligase complex mediates proteasomal degradation of ZBTB7A. HSP90 inhibition (by 17-AAG) triggers p53-dependent upregulation of KLHL20, leading to ZBTB7A proteolysis and derepression of p21/CDKN1A.\",\n      \"method\": \"Co-immunoprecipitation, protein stability assays, siRNA knockdown, HSP90 inhibitor treatment, Western blotting\",\n      \"journal\": \"Biochimica et biophysica acta. Gene regulatory mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, knockdown, protein stability assays; single lab, multiple methods\",\n      \"pmids\": [\"37011832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"KLHL20 interacts with ZFTA (zinc finger translocation associated protein) via its Kelch domain with an estimated KD ~35 µM, exhibiting 'fuzzy binding' through feature-specific rather than sequence-specific recognition. The interaction specificity for KLHL20 vs. KLHL12 was confirmed. This mechanism reflects KLHL20's role as an adaptor for disordered substrate recognition.\",\n      \"method\": \"Biosensor (SPR/BLI) analysis, AlphaFold2-based structural modeling, truncation peptide binding experiments\",\n      \"journal\": \"Chembiochem\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — biosensor analysis with computational modeling, single study, no in-cell ubiquitination confirmation reported in abstract\",\n      \"pmids\": [\"41762441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Under high glucose conditions, KLHL20 expression is transcriptionally suppressed, leading to reduced DAPK1 ubiquitination and elevated DAPK1 protein levels that promote mitochondrial apoptosis in renal tubular cells. KLHL20 overexpression restores DAPK1 ubiquitination and reduces protein levels (without affecting mRNA), confirming KLHL20 as an E3 adaptor for DAPK1 post-translational regulation in this context.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assay, KLHL20 overexpression, DAPK1 knockdown, protein stability/half-life assay, db/db mouse model, HK-2 cell model\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP, ubiquitination assay, OE/KD with functional rescue, in vivo model; single lab\",\n      \"pmids\": [\"41637987\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KLHL20 is a BTB-Kelch domain protein that functions as the substrate-adaptor subunit of a CUL3-ROC1 RING E3 ubiquitin ligase complex, recognizing substrates (DAPK1, PML, ULK1, VPS34/Beclin-1/ATG14, PDZ-RhoGEF, coronin 7, SERINC5, ZBTB7A) via its Kelch β-propeller domain and directing either degradative (K48-linked) or non-degradative (K33-linked) polyubiquitination; its subcellular localization (cytoplasm, TGN, or PML nuclear bodies) is dynamically regulated by stress signals (IFN, hypoxia, autophagy induction) to switch substrate targeting, thereby controlling autophagy termination, post-Golgi vesicle trafficking, RhoA-dependent neurite outgrowth, HIF-1α amplification in hypoxia, and IFN-induced DAPK-mediated cell death.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"KLHL20 is a BTB-Kelch protein that functions as the substrate-recognition subunit of a CUL3-ROC1 RING E3 ubiquitin ligase, in which its BTB domain engages Cul3 and its Kelch β-propeller domain captures substrates [#2]. A high-resolution structure of the Kelch domain bound to a DAPK1 death-domain peptide shows substrates insert an 'LPDLV' motif deep into the central pocket of the β-propeller to contact all six blades [#9], and KLHL20 directs both degradative (K48-linked) and non-degradative (K33-linked) polyubiquitination depending on substrate and signal [#5, #10]. Through this activity KLHL20 controls multiple cellular programs: it terminates autophagy by ubiquitinating the autophagy-initiating kinase ULK1 and governing turnover of VPS34, Beclin-1, ATG13 and ATG14 during prolonged starvation [#7]; it promotes post-Golgi vesicle trafficking from the trans-Golgi network by K33-linked ubiquitination of coronin 7, routing it via Eps15 to drive TGN F-actin assembly [#5]; and it restrains RhoA-dependent neurite outgrowth by degrading p38-phosphorylated PDZ-RhoGEF [#4]. KLHL20 activity is regulated at the level of localization and signaling: IFN-α/γ sequesters KLHL20 in PML nuclear bodies to stabilize DAPK and license IFN-induced apoptosis and autophagy [#2], while under hypoxia KLHL20 degrades PML in a CDK1/2- and Pin1-dependent feedback loop that amplifies HIF-1α and tumor hypoxia responses [#3]. Its substrate repertoire extends to SERINC5 (controlling plasma-membrane delivery versus degradation) [#10] and the transcriptional repressor ZBTB7A in a p53-induced axis that derepresses p21 [#12]. KLHL39, a related BTB-Kelch protein lacking Cul3-binding residues, antagonizes the ligase by occupying the Kelch domain and blocking both substrate and Cul3 engagement [#6]. De novo missense variants clustering in the substrate-binding β-propeller surface, including a recurrent Gly357Arg, cause a neurodevelopmental syndrome [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Before any enzymatic role was known, KLHL20 was placed in actin cytoskeletal dynamics, establishing an early link to Rac1-driven actin organization at nascent cell-cell contacts.\",\n      \"evidence\": \"Co-localization microscopy, E-cadherin-bead recruitment, and dominant-negative fragment expression in MDCK cells\",\n      \"pmids\": [\"14668487\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No molecular activity or E3 ligase role identified at this stage\", \"Mechanism connecting actin binding to later ubiquitin ligase function not defined\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"KLHL20 was tied to RhoA signaling in endothelial migration, showing it acts upstream of RhoA activation and physically associates with the GEF ECT2 during angiogenic responses.\",\n      \"evidence\": \"siRNA knockdown, sprouting angiogenesis assay, RhoA activation assays, and Co-IP of KLHL20 with ECT2 in endothelial cells\",\n      \"pmids\": [\"17395875\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether KLHL20-ECT2 interaction is ubiquitination-dependent unresolved\", \"Single lab, single Co-IP for the interaction\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"The defining mechanistic advance: KLHL20 was shown to be a CUL3-ROC1 substrate adaptor that degrades DAPK, and stress-induced sequestration in PML bodies emerged as a localization switch controlling substrate access.\",\n      \"evidence\": \"Reciprocal Co-IP, ubiquitination assay, BTB/Kelch domain mapping, siRNA, and IFN-induced relocalization to PML nuclear bodies\",\n      \"pmids\": [\"20389280\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Structural basis of DAPK recognition not yet resolved\", \"Generality of PML sequestration to other substrates unknown\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"KLHL20 was connected to hypoxia and neuronal morphogenesis by identifying PML and PDZ-RhoGEF as substrates, revealing kinase-gated substrate recruitment (CDK1/2-Pin1 and p38) and a HIF-1α amplification feedback loop.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, genetic epistasis, xenograft and primary neuron models with kinase inhibition\",\n      \"pmids\": [\"21840486\", \"21670212\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How a single adaptor coordinates context-specific substrate selection unresolved\", \"Direct versus indirect degradation of some downstream factors not fully separated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"KLHL20 was assigned a non-degradative ubiquitin function and a TGN localization, demonstrating K33-linked ubiquitination of coronin 7 to drive post-Golgi carrier biogenesis, broadening its output beyond proteolysis.\",\n      \"evidence\": \"In vitro linkage-specific ubiquitination, K33R ubiquitin mutants, Co-IP, subcellular fractionation, and enforced-targeting epistasis\",\n      \"pmids\": [\"24768539\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"How KLHL20 selects K33 versus K48 linkage at the molecular level unknown\", \"Determinants of TGN recruitment of KLHL20 itself not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"A KLHL20 knockout mouse linked it to HIF-2α stabilization and VEGF expression in lung endothelium, reinforcing a hypoxia-signaling role in vivo.\",\n      \"evidence\": \"KLEIP knockout mice, immunohistochemistry, expression analysis, and betamethasone rescue\",\n      \"pmids\": [\"24785085\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Direct ubiquitin-mediated mechanism on HIF-2α not established\", \"Relationship to the PML/HIF-1α feedback loop unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"KLHL20 was established as the terminator of autophagy via ULK1 ubiquitination and turnover of multiple autophagy regulators, and a negative regulator (KLHL39) was identified that blocks the ligase by occupying its Kelch domain.\",\n      \"evidence\": \"Co-IP, ubiquitination assays, knockout mouse and diabetes models, in vitro kinase assays (ULK1); domain-mapping and rescue (KLHL39)\",\n      \"pmids\": [\"26687681\", \"25619834\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Which autophagy substrates are direct versus indirect not fully resolved\", \"Physiological signals controlling KLHL39 expression unknown\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"A 1.1 Å crystal structure of the Kelch domain with a DAPK1 peptide defined the substrate-recognition mechanism, showing the LPDLV motif buried in the β-propeller central pocket.\",\n      \"evidence\": \"X-ray crystallography with peptide binding and mutagenesis\",\n      \"pmids\": [\"31279627\"],\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Whether all substrates share an LPDLV-like motif not established\", \"Structure of the full CUL3-bound complex absent\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Substrate scope and disease relevance expanded: KLHL20 was shown to dual-ubiquitinate SERINC5 to balance surface delivery versus degradation, and de novo Kelch-domain variants were linked to a neurodevelopmental syndrome.\",\n      \"evidence\": \"Linkage-specific ubiquitination and flow cytometry (SERINC5); patient cohort genotyping and variant mapping (neurodevelopmental syndrome)\",\n      \"pmids\": [\"35474067\", \"36214804\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No direct functional assay of patient variants reported\", \"Which neuronal substrates underlie the disorder unidentified\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"KLHL20 was placed downstream of p53, mediating ZBTB7A degradation upon HSP90 inhibition and thereby derepressing p21, extending its reach into transcriptional and cell-cycle control.\",\n      \"evidence\": \"Co-IP, protein stability assays, siRNA, and HSP90 inhibitor treatment\",\n      \"pmids\": [\"37011832\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"Single lab; ubiquitination linkage on ZBTB7A not characterized\", \"Direct versus indirect p21 derepression not separated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Disease-context regulation and a 'fuzzy' substrate-binding mode were probed: high-glucose suppression of KLHL20 elevates DAPK1 to drive renal tubular apoptosis, and biosensor/computational work characterized low-affinity feature-specific recognition of ZFTA.\",\n      \"evidence\": \"Co-IP, ubiquitination and half-life assays with db/db and HK-2 models (DAPK1); SPR/BLI and AlphaFold2 modeling (ZFTA)\",\n      \"pmids\": [\"41637987\", \"41762441\"],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"ZFTA finding is Low confidence with no in-cell ubiquitination confirmation\", \"How fuzzy binding reconciles with the defined LPDLV pocket mode unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how a single Kelch adaptor achieves context-dependent selection among its many substrates and how the choice between K33- and K48-linked chains is mechanistically encoded.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"\",\n      \"gaps\": [\"No unifying model for linkage-type determination\", \"No structure of the assembled CUL3-KLHL20 complex with substrate\", \"Patient variant consequences not functionally tested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 3, 4, 5, 7, 10]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [2, 5, 7, 10]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 9, 13]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [5, 10]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0016605\", \"supporting_discovery_ids\": [2]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [2, 3, 4, 5, 7, 10]},\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [5, 10]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [2, 14]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [2, 3, 7]}\n    ],\n    \"complexes\": [\"CUL3-ROC1 (Cullin-RING) E3 ubiquitin ligase\"],\n    \"partners\": [\"CUL3\", \"DAPK1\", \"PML\", \"ULK1\", \"PDZ-RhoGEF (ARHGEF11)\", \"SERINC5\", \"KLHL39\", \"ECT2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":7,"faith_pct":85.71428571428571}}