{"gene":"BCKDK","run_date":"2026-04-28T17:12:38","timeline":{"discoveries":[{"year":2014,"finding":"BCKDK phosphorylates the E1α subunit of the branched-chain α-keto acid dehydrogenase complex (BCKD), inactivating it and thereby negatively regulating BCAA catabolism. Loss-of-function mutations in BCKDK (p.R174Gfs1* and p.L389P) result in undetectable phospho-E1α, increased BCKD activity, and rapid BCAA catabolism in patient fibroblasts.","method":"Functional analysis of patient-derived fibroblasts (western blot for phospho-E1α, kinase activity assay), mutagenesis characterization","journal":"Human mutation","confidence":"High","confidence_rationale":"Tier 2 — loss-of-function mutations with direct biochemical readout (phospho-substrate loss) replicated across two independent patients","pmids":["24449431"],"is_preprint":false},{"year":2017,"finding":"BCKDK promotes colorectal cancer cell transformation by directly phosphorylating MEK to activate the MAPK/ERK signaling pathway, independent of its role in BCAA catabolism.","method":"Co-immunoprecipitation, western blot for MEK phosphorylation, cell transformation assays, pharmacological inhibition with phenyl butyrate","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 3 — single lab, direct MEK phosphorylation shown by IP/western blot with functional rescue","pmids":["28501528"],"is_preprint":false},{"year":2019,"finding":"UBE3B (E3 ubiquitin ligase mutated in Kaufman oculocerebrofacial syndrome) targets BCKDK as an in vivo substrate; loss of UBE3B perturbs BCKDK-regulated metabolic pathways including nucleotide metabolism and TCA cycle.","method":"Identification of UBE3B interactors by proteomics, in vivo substrate validation in Ube3b-/- mice, metabolomic profiling","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo substrate identification with metabolomic validation, single lab","pmids":["30808755"],"is_preprint":false},{"year":2020,"finding":"Src kinase phosphorylates BCKDK at tyrosine 246 (Y246), enhancing BCKDK activity and stability, which promotes CRC cell migration, invasion, and epithelial-mesenchymal transition.","method":"In vitro kinase assay, co-immunoprecipitation, Src knockdown/knockout reducing p-BCKDK(Y246), phosphoproteomics, migration/invasion assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro and ex vivo phosphorylation confirmed, genetic KO of Src validates the modification, multiple orthogonal methods","pmids":["32238881"],"is_preprint":false},{"year":2020,"finding":"APN (aminopeptidase N/CD13) mediates phosphorylation of BCKDK at serine 31 (S31), promoting BCKDK interaction with ERK1/2 and its phosphorylation, thereby activating ERK signaling to drive HCC proliferation and metastasis.","method":"Phosphoproteomic analysis, western blot with point mutation, co-immunoprecipitation, proximity ligation assay, APN knockout","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods in single lab confirming phosphorylation and interaction","pmids":["32457292"],"is_preprint":false},{"year":2021,"finding":"BCKDK serves as a compensatory kinase for pyruvate dehydrogenase complex (PDC) when all four PDK family members are absent during murine embryonic development. Knockout of Bckdk in PDK-total-KO embryos abolishes PDC phosphorylation, increases PDC activity and pyruvate entry into the TCA cycle, and causes embryonic lethality.","method":"Sequential knockout of Pdk1-4 genes in mice, Bckdk/Pdk combined KO, measurement of PDC phosphorylation status and activity, metabolic flux analysis","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1–2 — genetic epistasis with direct biochemical measurement of PDC phosphorylation; multiple knockout alleles tested","pmids":["33773101"],"is_preprint":false},{"year":2021,"finding":"BCKDK silencing in triple-negative breast cancer cells reduces mitochondrial electron transport complex protein expression, oxygen consumption, and ATP production, and upregulates sestrin 2 while decreasing mTORC1 signaling and protein synthesis.","method":"Genetic knockdown and pharmacological inhibition of BCKDK, transcriptome analysis, oxygen consumption rate measurements, mTORC1 pathway western blot","journal":"Cell death discovery","confidence":"Medium","confidence_rationale":"Tier 2 — multiple functional readouts with genetic and pharmacological inhibition, single lab","pmids":["34526485"],"is_preprint":false},{"year":2023,"finding":"BCKDK phosphorylates BCAT1 at S5, S9, and T312 to increase its catalytic/antioxidant activity and stability; BCKDK also phosphorylates the E3 ubiquitin ligase STUB1 at S19, disrupting the STUB1–BCAT1 interaction and preventing BCAT1 ubiquitination and degradation in glioblastoma.","method":"In vitro kinase assays, co-immunoprecipitation, point mutation analysis, mass spectrometry, in vivo tumor models","journal":"Cancer letters","confidence":"High","confidence_rationale":"Tier 1 — in vitro phosphorylation reconstituted, site-specific mutagenesis, multiple substrates identified with orthogonal methods","pmids":["38621458"],"is_preprint":false},{"year":2023,"finding":"BCKDK inhibits the binding of talin1 to E3 ubiquitin ligase TRIM21, reducing talin1 ubiquitination/degradation and activating the FAK/MAPK pathway to promote breast cancer cell migration.","method":"Co-immunoprecipitation, ubiquitination assays, BCKDK knockdown with migration assays in vitro and lung metastasis in vivo","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2–3 — interaction and ubiquitination mechanism supported by Co-IP and functional rescue, single lab","pmids":["37460470"],"is_preprint":false},{"year":2024,"finding":"Fyn kinase phosphorylates BCKDK at tyrosine 151 (Y151), increasing BCKDK catalytic activity and stability in glioblastoma. Elevated BCKDK activity increases the oncogenic metabolite N-acetyl-L-alanine (NAAL), which activates ERK signaling to promote GBM proliferation.","method":"In vitro and in vivo kinase assays, site-directed mutagenesis, metabolomics, BCKDK silencing/inhibition experiments","journal":"Heliyon","confidence":"Medium","confidence_rationale":"Tier 1–2 — in vitro phosphorylation with mutagenesis, metabolomics validation, single lab","pmids":["39170503"],"is_preprint":false},{"year":2024,"finding":"BCKDK interacts with and stabilizes the NDUFS1 subunit of mitochondrial Complex I; loss of BCKDK disrupts this interaction, leading to Complex I destabilization, reduced membrane potential, increased ROS, and promotion of α-synuclein oligomerization in dopaminergic neuron models of Parkinson's disease.","method":"Co-immunoprecipitation of BCKDK–NDUFS1, Complex I activity assays, mitochondrial membrane potential and ROS measurements, BCKDK rescue experiments in iPS-derived dopaminergic neurons","journal":"Acta neuropathologica communications","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding partner identified by Co-IP, functional rescue in patient-derived neurons; single lab","pmids":["39709505"],"is_preprint":false},{"year":2024,"finding":"Nuclear-localized BCKDK phosphorylates RNF8 at Ser157, preventing ubiquitin-mediated degradation of RAD51 and thereby facilitating homologous recombination repair of DNA damage in breast cancer cells, independent of BCKDK's metabolic function.","method":"Subcellular fractionation showing nuclear BCKDK, co-immunoprecipitation, kinase assay, site-directed mutagenesis, RAD51 ubiquitination assay, DNA damage repair assays","journal":"Advanced science","confidence":"Medium","confidence_rationale":"Tier 2 — nuclear localization demonstrated by fractionation, phosphorylation site mapped with mutagenesis, functional HRR readout; single lab","pmids":["40298908"],"is_preprint":false},{"year":2024,"finding":"BCKDK interacts with glucose-6-phosphate dehydrogenase (G6PD), stabilizing it and increasing flux through the pentose phosphate pathway for macromolecule synthesis and ROS detoxification in triple-negative breast cancer.","method":"Co-immunoprecipitation, mass spectrometry, isotope tracer studies (13C), immunofluorescence, rescue with forced G6PD expression","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 — interaction confirmed by Co-IP/MS and isotope tracing with functional rescue; single lab","pmids":["39025830"],"is_preprint":false},{"year":2024,"finding":"PSMD14 (a deubiquitinase) directly interacts with BCKDK and deubiquitinates it, antagonizing TRIM21-mediated proteasomal degradation and stabilizing BCKDK protein levels in glioblastoma.","method":"Co-immunoprecipitation, deubiquitination assay, PSMD14 knockdown with BCKDK protein level measurement","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 — direct deubiquitinase activity on BCKDK demonstrated, antagonism with TRIM21 established; single lab","pmids":["41876842"],"is_preprint":false},{"year":2024,"finding":"BCKDK interacts with and phosphorylates BCLAF1 at serine 285, facilitating BCLAF1 binding to the MYC promoter, enhancing MYC transcription, upregulating hexokinase 2, and promoting aerobic glycolysis and Trametinib resistance in lung cancer.","method":"Co-immunoprecipitation, phosphorylation assay, chromatin immunoprecipitation (ChIP) showing BCLAF1 at MYC promoter, BCKDK knockdown/overexpression with downstream pathway analysis","journal":"Cell death and differentiation","confidence":"Medium","confidence_rationale":"Tier 2 — phosphorylation and transcriptional mechanism supported by Co-IP, ChIP, and functional experiments; single lab","pmids":["40442441"],"is_preprint":false},{"year":2025,"finding":"In zebrafish, Bckdk phosphorylates the chromatin remodeling factor Phf10/Baf45a; loss of Bckdk reduces Phf10 phosphorylation, leading to epiboly defects, zygotic genome activation deregulation, and impaired miR-430 processing during the maternal-to-zygotic transition.","method":"CRISPR-RfxCas13d maternal mRNA knockdown screen, phospho-proteomics, phf10 knockdown epistasis, rescue with phospho-mimetic Phf10 mutant","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1–2 — substrate identified by phospho-proteomics, genetic epistasis confirmed, rescue with phospho-mimetic mutant; multiple orthogonal methods","pmids":["41254269"],"is_preprint":false},{"year":2025,"finding":"PRSS55 (serine protease 55) interacts with BCKDK and its substrate BCKDHA in mouse testes and sperm mitochondria, regulating BCAA metabolism and mitochondrial energy homeostasis to facilitate sperm function.","method":"LC-MS/MS proteomics and co-immunoprecipitation validating PRSS55–BCKDK and PRSS55–BCKDHA interactions; metabolomics showing BCAA accumulation in Prss55-/- testes","journal":"Cell & bioscience","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP and proteomics in single lab; functional connection via metabolomics in KO model","pmids":["41444608"],"is_preprint":false},{"year":2016,"finding":"BCKDK deficiency in patient fibroblasts causes increased superoxide anion production, reduced ATP-linked respiration, and mitochondrial hyperfusion associated with changes in OPA1 and MFN2, demonstrating that BCKDK activity is required for normal mitochondrial bioenergetics and dynamics.","method":"Oxygen consumption rate measurement, ATP quantification, ROS assay, electron microscopy ultrastructure analysis, BCKDK knockdown in control fibroblasts recapitulating phenotypes","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 — multiple bioenergetic parameters measured with genetic knockdown recapitulation; single lab","pmids":["26809120"],"is_preprint":false}],"current_model":"BCKDK is a mitochondria-associated serine/threonine kinase that primarily phosphorylates and inactivates the E1α subunit of the branched-chain α-keto acid dehydrogenase complex (BCKDH) to restrain BCAA catabolism; beyond this canonical metabolic role, BCKDK also phosphorylates non-metabolic substrates including MEK, RNF8, BCLAF1, BCAT1, STUB1, and Phf10/Baf45a, interacts with mitochondrial Complex I subunit NDUFS1 to stabilize respiratory chain function, localizes to the nucleus to facilitate homologous recombination repair, and is itself regulated by upstream kinases (Src at Y246, Fyn at Y151) and ubiquitin ligases (TRIM21, UBE3B) that control its stability and activity."},"narrative":{"teleology":[{"year":2014,"claim":"Establishing the core enzymatic function: patient loss-of-function mutations demonstrated that BCKDK is the kinase responsible for phosphorylating and inactivating BCKDH-E1α, defining its role as the master negative regulator of BCAA catabolism.","evidence":"Biochemical analysis of patient-derived fibroblasts with BCKDK mutations showing undetectable phospho-E1α and increased BCKD activity","pmids":["24449431"],"confidence":"High","gaps":["Structural basis for E1α recognition not resolved","Whether BCKDK has additional mitochondrial substrates was unknown"]},{"year":2016,"claim":"BCKDK deficiency was shown to impair mitochondrial bioenergetics and dynamics, revealing that the kinase's function extends beyond substrate-level metabolic regulation to maintenance of respiratory chain function and mitochondrial morphology.","evidence":"Oxygen consumption, ATP, ROS, and electron microscopy in BCKDK-deficient patient fibroblasts with knockdown recapitulation","pmids":["26809120"],"confidence":"Medium","gaps":["Direct mitochondrial target(s) mediating bioenergetic and morphological changes were not identified","Whether the effect is secondary to BCAA imbalance was not excluded"]},{"year":2017,"claim":"The discovery that BCKDK directly phosphorylates MEK to activate ERK signaling in colorectal cancer established the first non-metabolic substrate and linked BCKDK to oncogenic MAPK pathway activation.","evidence":"Co-immunoprecipitation, MEK phosphorylation western blot, and cell transformation assays with pharmacological inhibition","pmids":["28501528"],"confidence":"Medium","gaps":["Specific MEK phosphorylation site not mapped","Independence from BCAA effects inferred but not fully dissected genetically"]},{"year":2019,"claim":"Identification of BCKDK as an in vivo substrate of the E3 ligase UBE3B revealed that BCKDK protein levels are controlled by ubiquitin-dependent degradation, connecting its regulation to Kaufman oculocerebrofacial syndrome-associated metabolic perturbations.","evidence":"Proteomics-based substrate identification and metabolomic profiling in Ube3b-knockout mice","pmids":["30808755"],"confidence":"Medium","gaps":["Specific ubiquitination sites on BCKDK by UBE3B not mapped","Functional consequence of UBE3B loss on BCKDK activity not directly measured"]},{"year":2020,"claim":"Src and APN-mediated phosphorylation of BCKDK at Y246 and S31, respectively, established that BCKDK is itself subject to upstream kinase regulation that modulates both its catalytic activity and its engagement with ERK signaling.","evidence":"In vitro kinase assays, phosphoproteomics, Src-KO validation, point mutation analysis, and proximity ligation assay","pmids":["32238881","32457292"],"confidence":"High","gaps":["Whether Y246 and S31 phosphorylation are coordinated or independent events is unknown","The phosphatase(s) opposing these modifications are unidentified"]},{"year":2021,"claim":"Genetic epistasis in mice revealed BCKDK as a compensatory kinase for the pyruvate dehydrogenase complex (PDC) when all four PDK isoforms are absent, demonstrating substrate promiscuity with developmental significance.","evidence":"Sequential Pdk1-4 knockout combined with Bckdk knockout in mice; PDC phosphorylation and metabolic flux analysis","pmids":["33773101"],"confidence":"High","gaps":["Whether BCKDK phosphorylates PDC under physiological conditions with PDKs present is unclear","Specific PDC subunit phosphorylation sites targeted by BCKDK not fully resolved"]},{"year":2021,"claim":"BCKDK silencing reduced mitochondrial electron transport chain protein expression, oxygen consumption, and mTORC1 signaling in breast cancer cells, reinforcing a broader role in mitochondrial and growth-regulatory homeostasis beyond BCAA catabolism.","evidence":"Genetic knockdown and pharmacological inhibition with transcriptomics, OCR, and mTORC1 pathway readouts in TNBC cells","pmids":["34526485"],"confidence":"Medium","gaps":["Direct versus indirect effects on ETC complex expression not distinguished","Whether sestrin 2 upregulation is a direct phosphorylation target or transcriptional response is unknown"]},{"year":2023,"claim":"BCKDK was shown to phosphorylate both BCAT1 (enhancing its activity) and STUB1 (disrupting BCAT1 ubiquitination), revealing a dual mechanism of substrate stabilization through direct phosphorylation and E3 ligase interference.","evidence":"In vitro kinase assays, mass spectrometry-based site mapping, point mutation analysis, and in vivo tumor models","pmids":["38621458"],"confidence":"High","gaps":["Whether the BCAT1-stabilizing mechanism operates outside glioblastoma contexts is untested","Crystal structure of BCKDK–BCAT1 interaction lacking"]},{"year":2023,"claim":"BCKDK was found to stabilize talin1 by blocking TRIM21-mediated ubiquitination, linking BCKDK to integrin-associated FAK/MAPK signaling and cell migration—expanding its non-catalytic scaffolding functions.","evidence":"Co-immunoprecipitation, ubiquitination assays, migration assays in vitro and lung metastasis in vivo","pmids":["37460470"],"confidence":"Medium","gaps":["Whether BCKDK directly phosphorylates talin1 or acts purely as a competitive binding partner for TRIM21 is unresolved","Single-lab finding without independent replication"]},{"year":2024,"claim":"Multiple studies expanded the BCKDK substrate repertoire and regulatory network: Fyn phosphorylates BCKDK at Y151 in glioblastoma; BCKDK interacts with and stabilizes NDUFS1 of Complex I to maintain mitochondrial membrane potential; nuclear BCKDK phosphorylates RNF8 to facilitate homologous recombination repair; BCKDK stabilizes G6PD to promote the pentose phosphate pathway; PSMD14 deubiquitinates BCKDK opposing TRIM21; and BCKDK phosphorylates BCLAF1 to activate MYC transcription.","evidence":"Kinase assays, Co-IP, subcellular fractionation, ChIP, isotope tracing, deubiquitination assays, iPSC-derived neuron models, and tumor models across multiple independent studies","pmids":["39170503","39709505","40298908","39025830","41876842","40442441"],"confidence":"Medium","gaps":["Most non-metabolic substrates identified in single labs without independent replication","Structural basis for BCKDK's nuclear localization signal not identified","Relative physiological importance of metabolic versus non-metabolic BCKDK functions is unranked"]},{"year":2025,"claim":"BCKDK was shown to phosphorylate the chromatin remodeling factor Phf10/Baf45a in zebrafish, establishing an essential role during the maternal-to-zygotic transition through regulation of zygotic genome activation and miR-430 processing.","evidence":"CRISPR-RfxCas13d maternal knockdown screen, phospho-proteomics, genetic epistasis, and phospho-mimetic rescue in zebrafish embryos","pmids":["41254269"],"confidence":"High","gaps":["Whether the BCKDK–Phf10 axis is conserved in mammals is unknown","Mechanism by which Phf10 phosphorylation controls miR-430 processing not fully elucidated"]},{"year":null,"claim":"A unifying structural and systems-level understanding of how BCKDK achieves substrate selectivity across its diverse metabolic and non-metabolic targets, and how its mitochondrial, cytoplasmic, and nuclear pools are differentially regulated, remains to be established.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of full-length BCKDK bound to non-BCKDH substrates","Relative contribution of BCKDK kinase activity versus scaffolding to each phenotype not systematically tested","How BCKDK is partitioned among subcellular compartments is mechanistically unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3,5,7,9,11,14,15]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,10,16,17]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[11]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,2,5,6,12,16]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,4,9,14]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[11]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[7,8,13]}],"complexes":["BCKDH complex (as regulatory kinase)"],"partners":["BCKDHA","MEK","NDUFS1","BCAT1","STUB1","RNF8","BCLAF1","G6PD"],"other_free_text":[]},"mechanistic_narrative":"BCKDK is a mitochondria-associated serine/threonine kinase that controls branched-chain amino acid (BCAA) catabolism by phosphorylating and inactivating the E1α subunit of the branched-chain α-keto acid dehydrogenase complex (BCKDH), and also phosphorylates the pyruvate dehydrogenase complex when canonical PDK kinases are absent [PMID:24449431, PMID:33773101]. Beyond metabolic regulation, BCKDK phosphorylates diverse non-metabolic substrates—including MEK, BCAT1, STUB1, RNF8, BCLAF1, and the chromatin remodeling factor Phf10/Baf45a—thereby engaging MAPK/ERK signaling, DNA homologous recombination repair, MYC-driven glycolysis, and zygotic genome activation [PMID:28501528, PMID:38621458, PMID:40298908, PMID:40442441, PMID:41254269]. BCKDK activity and stability are regulated by upstream tyrosine kinases Src (at Y246) and Fyn (at Y151) and by opposing ubiquitin-mediated turnover through TRIM21 and the deubiquitinase PSMD14, while the E3 ligase UBE3B also targets BCKDK as an in vivo substrate [PMID:32238881, PMID:39170503, PMID:41876842, PMID:30808755]. Loss-of-function mutations in BCKDK cause a Mendelian disorder characterized by reduced plasma BCAAs with increased BCKDH activity, and BCKDK deficiency additionally disrupts mitochondrial Complex I stability, bioenergetics, and dynamics [PMID:24449431, PMID:26809120, PMID:39709505]."},"prefetch_data":{"uniprot":{"accession":"O14874","full_name":"Branched-chain alpha-ketoacid dehydrogenase kinase","aliases":["[3-methyl-2-oxobutanoate dehydrogenase [lipoamide]] kinase, mitochondrial"],"length_aa":412,"mass_kda":46.4,"function":"Serine/threonine-protein kinase component of macronutrients metabolism. Forms a functional kinase and phosphatase pair with PPM1K, serving as a metabolic regulatory node that coordinates branched-chain amino acids (BCAAs) with glucose and lipid metabolism via two distinct phosphoprotein targets: mitochondrial BCKDHA subunit of the branched-chain alpha-ketoacid dehydrogenase (BCKDH) complex and cytosolic ACLY, a lipogenic enzyme of Krebs cycle (PubMed:24449431, PubMed:29779826, PubMed:37558654). Phosphorylates and inactivates mitochondrial BCKDH complex a multisubunit complex consisting of three multimeric components each involved in different steps of BCAA catabolism: E1 composed of BCKDHA and BCKDHB, E2 core composed of DBT monomers, and E3 composed of DLD monomers. Associates with the E2 component of BCKDH complex and phosphorylates BCKDHA on Ser-337, leading to conformational changes that interrupt substrate channeling between E1 and E2 and inactivates the BCKDH complex (PubMed:29779826, PubMed:37558654). Phosphorylates ACLY on Ser-455 in response to changes in cellular carbohydrate abundance such as occurs during fasting to feeding metabolic transition. Refeeding stimulates MLXIPL/ChREBP transcription factor, leading to increased BCKDK to PPM1K expression ratio, phosphorylation and activation of ACLY that ultimately results in the generation of malonyl-CoA and oxaloacetate immediate substrates of de novo lipogenesis and glucogenesis, respectively (PubMed:29779826). Recognizes phosphosites having SxxE/D canonical motif (PubMed:29779826)","subcellular_location":"Mitochondrion matrix","url":"https://www.uniprot.org/uniprotkb/O14874/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/BCKDK","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"TJP2","stoichiometry":4.0},{"gene":"CPSF6","stoichiometry":0.2},{"gene":"HNRNPH1","stoichiometry":0.2},{"gene":"MAP4","stoichiometry":0.2},{"gene":"RBM39","stoichiometry":0.2},{"gene":"SNX9","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/BCKDK","total_profiled":1310},"omim":[{"mim_id":"614923","title":"BRANCHED-CHAIN KETO ACID DEHYDROGENASE KINASE DEFICIENCY; BCKDKD","url":"https://www.omim.org/entry/614923"},{"mim_id":"614901","title":"BRANCHED-CHAIN ALPHA-KETO ACID DEHYDROGENASE KINASE; BCKDK","url":"https://www.omim.org/entry/614901"},{"mim_id":"611065","title":"PROTEIN PHOSPHATASE, MAGNESIUM/MANGANESE-DEPENDENT, 1K; PPM1K","url":"https://www.omim.org/entry/611065"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mitochondria","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/BCKDK"},"hgnc":{"alias_symbol":[],"prev_symbol":[]},"alphafold":{"accession":"O14874","domains":[{"cath_id":"1.20.140.20","chopping":"56-219","consensus_level":"high","plddt":91.1484,"start":56,"end":219},{"cath_id":"3.30.565.10","chopping":"224-347_362-402","consensus_level":"high","plddt":92.3727,"start":224,"end":402}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O14874","model_url":"https://alphafold.ebi.ac.uk/files/AF-O14874-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O14874-F1-predicted_aligned_error_v6.png","plddt_mean":83.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=BCKDK","jax_strain_url":"https://www.jax.org/strain/search?query=BCKDK"},"sequence":{"accession":"O14874","fasta_url":"https://rest.uniprot.org/uniprotkb/O14874.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O14874/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O14874"}},"corpus_meta":[{"pmid":"24449431","id":"PMC_24449431","title":"Two novel mutations in the BCKDK (branched-chain keto-acid dehydrogenase kinase) gene are responsible for a neurobehavioral deficit in two pediatric unrelated patients.","date":"2014","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/24449431","citation_count":64,"is_preprint":false},{"pmid":"32238881","id":"PMC_32238881","title":"Phosphorylation of BCKDK of BCAA catabolism at Y246 by Src promotes metastasis of colorectal cancer.","date":"2020","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/32238881","citation_count":63,"is_preprint":false},{"pmid":"28501528","id":"PMC_28501528","title":"BCKDK of BCAA Catabolism Cross-talking With the MAPK Pathway Promotes Tumorigenesis of Colorectal Cancer.","date":"2017","source":"EBioMedicine","url":"https://pubmed.ncbi.nlm.nih.gov/28501528","citation_count":56,"is_preprint":false},{"pmid":"37460470","id":"PMC_37460470","title":"BCKDK regulates breast cancer cell adhesion and tumor metastasis by inhibiting TRIM21 ubiquitinate talin1.","date":"2023","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/37460470","citation_count":41,"is_preprint":false},{"pmid":"32457292","id":"PMC_32457292","title":"APN-mediated phosphorylation of BCKDK promotes hepatocellular carcinoma metastasis and proliferation via the ERK signaling pathway.","date":"2020","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/32457292","citation_count":39,"is_preprint":false},{"pmid":"34526485","id":"PMC_34526485","title":"Inhibiting BCKDK in triple negative breast cancer suppresses protein translation, impairs mitochondrial function, and potentiates doxorubicin cytotoxicity.","date":"2021","source":"Cell death discovery","url":"https://pubmed.ncbi.nlm.nih.gov/34526485","citation_count":34,"is_preprint":false},{"pmid":"35070754","id":"PMC_35070754","title":"BCKDK alters the metabolism of non-small cell lung cancer.","date":"2021","source":"Translational lung cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/35070754","citation_count":34,"is_preprint":false},{"pmid":"26809120","id":"PMC_26809120","title":"Mitochondrial response to the BCKDK-deficiency: Some clues to understand the positive dietary response in this form of autism.","date":"2016","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/26809120","citation_count":29,"is_preprint":false},{"pmid":"30808755","id":"PMC_30808755","title":"The ubiquitin ligase UBE3B, disrupted in intellectual disability and absent speech, regulates metabolic pathways by targeting BCKDK.","date":"2019","source":"Proceedings of the National Academy of Sciences of the United States of America","url":"https://pubmed.ncbi.nlm.nih.gov/30808755","citation_count":28,"is_preprint":false},{"pmid":"36729635","id":"PMC_36729635","title":"BCKDK deficiency: a treatable neurodevelopmental disease amenable to newborn screening.","date":"2023","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/36729635","citation_count":24,"is_preprint":false},{"pmid":"33773101","id":"PMC_33773101","title":"BCKDK regulates the TCA cycle through PDC in the absence of PDK family during embryonic development.","date":"2021","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/33773101","citation_count":20,"is_preprint":false},{"pmid":"38734897","id":"PMC_38734897","title":"BCKDK modification enhances the anticancer efficacy of CAR-T cells by reprogramming branched chain amino acid metabolism.","date":"2024","source":"Molecular therapy : the journal of the American Society of Gene Therapy","url":"https://pubmed.ncbi.nlm.nih.gov/38734897","citation_count":18,"is_preprint":false},{"pmid":"35498541","id":"PMC_35498541","title":"BCKDK Promotes Ovarian Cancer Proliferation and Migration by Activating the MEK/ERK Signaling Pathway.","date":"2022","source":"Journal of 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Loss-of-function mutations in BCKDK (p.R174Gfs1* and p.L389P) result in undetectable phospho-E1α, increased BCKD activity, and rapid BCAA catabolism in patient fibroblasts.\",\n      \"method\": \"Functional analysis of patient-derived fibroblasts (western blot for phospho-E1α, kinase activity assay), mutagenesis characterization\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — loss-of-function mutations with direct biochemical readout (phospho-substrate loss) replicated across two independent patients\",\n      \"pmids\": [\"24449431\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"BCKDK promotes colorectal cancer cell transformation by directly phosphorylating MEK to activate the MAPK/ERK signaling pathway, independent of its role in BCAA catabolism.\",\n      \"method\": \"Co-immunoprecipitation, western blot for MEK phosphorylation, cell transformation assays, pharmacological inhibition with phenyl butyrate\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single lab, direct MEK phosphorylation shown by IP/western blot with functional rescue\",\n      \"pmids\": [\"28501528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"UBE3B (E3 ubiquitin ligase mutated in Kaufman oculocerebrofacial syndrome) targets BCKDK as an in vivo substrate; loss of UBE3B perturbs BCKDK-regulated metabolic pathways including nucleotide metabolism and TCA cycle.\",\n      \"method\": \"Identification of UBE3B interactors by proteomics, in vivo substrate validation in Ube3b-/- mice, metabolomic profiling\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo substrate identification with metabolomic validation, single lab\",\n      \"pmids\": [\"30808755\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Src kinase phosphorylates BCKDK at tyrosine 246 (Y246), enhancing BCKDK activity and stability, which promotes CRC cell migration, invasion, and epithelial-mesenchymal transition.\",\n      \"method\": \"In vitro kinase assay, co-immunoprecipitation, Src knockdown/knockout reducing p-BCKDK(Y246), phosphoproteomics, migration/invasion assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro and ex vivo phosphorylation confirmed, genetic KO of Src validates the modification, multiple orthogonal methods\",\n      \"pmids\": [\"32238881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"APN (aminopeptidase N/CD13) mediates phosphorylation of BCKDK at serine 31 (S31), promoting BCKDK interaction with ERK1/2 and its phosphorylation, thereby activating ERK signaling to drive HCC proliferation and metastasis.\",\n      \"method\": \"Phosphoproteomic analysis, western blot with point mutation, co-immunoprecipitation, proximity ligation assay, APN knockout\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in single lab confirming phosphorylation and interaction\",\n      \"pmids\": [\"32457292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"BCKDK serves as a compensatory kinase for pyruvate dehydrogenase complex (PDC) when all four PDK family members are absent during murine embryonic development. Knockout of Bckdk in PDK-total-KO embryos abolishes PDC phosphorylation, increases PDC activity and pyruvate entry into the TCA cycle, and causes embryonic lethality.\",\n      \"method\": \"Sequential knockout of Pdk1-4 genes in mice, Bckdk/Pdk combined KO, measurement of PDC phosphorylation status and activity, metabolic flux analysis\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — genetic epistasis with direct biochemical measurement of PDC phosphorylation; multiple knockout alleles tested\",\n      \"pmids\": [\"33773101\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"BCKDK silencing in triple-negative breast cancer cells reduces mitochondrial electron transport complex protein expression, oxygen consumption, and ATP production, and upregulates sestrin 2 while decreasing mTORC1 signaling and protein synthesis.\",\n      \"method\": \"Genetic knockdown and pharmacological inhibition of BCKDK, transcriptome analysis, oxygen consumption rate measurements, mTORC1 pathway western blot\",\n      \"journal\": \"Cell death discovery\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple functional readouts with genetic and pharmacological inhibition, single lab\",\n      \"pmids\": [\"34526485\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BCKDK phosphorylates BCAT1 at S5, S9, and T312 to increase its catalytic/antioxidant activity and stability; BCKDK also phosphorylates the E3 ubiquitin ligase STUB1 at S19, disrupting the STUB1–BCAT1 interaction and preventing BCAT1 ubiquitination and degradation in glioblastoma.\",\n      \"method\": \"In vitro kinase assays, co-immunoprecipitation, point mutation analysis, mass spectrometry, in vivo tumor models\",\n      \"journal\": \"Cancer letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro phosphorylation reconstituted, site-specific mutagenesis, multiple substrates identified with orthogonal methods\",\n      \"pmids\": [\"38621458\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"BCKDK inhibits the binding of talin1 to E3 ubiquitin ligase TRIM21, reducing talin1 ubiquitination/degradation and activating the FAK/MAPK pathway to promote breast cancer cell migration.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, BCKDK knockdown with migration assays in vitro and lung metastasis in vivo\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — interaction and ubiquitination mechanism supported by Co-IP and functional rescue, single lab\",\n      \"pmids\": [\"37460470\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Fyn kinase phosphorylates BCKDK at tyrosine 151 (Y151), increasing BCKDK catalytic activity and stability in glioblastoma. Elevated BCKDK activity increases the oncogenic metabolite N-acetyl-L-alanine (NAAL), which activates ERK signaling to promote GBM proliferation.\",\n      \"method\": \"In vitro and in vivo kinase assays, site-directed mutagenesis, metabolomics, BCKDK silencing/inhibition experiments\",\n      \"journal\": \"Heliyon\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro phosphorylation with mutagenesis, metabolomics validation, single lab\",\n      \"pmids\": [\"39170503\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BCKDK interacts with and stabilizes the NDUFS1 subunit of mitochondrial Complex I; loss of BCKDK disrupts this interaction, leading to Complex I destabilization, reduced membrane potential, increased ROS, and promotion of α-synuclein oligomerization in dopaminergic neuron models of Parkinson's disease.\",\n      \"method\": \"Co-immunoprecipitation of BCKDK–NDUFS1, Complex I activity assays, mitochondrial membrane potential and ROS measurements, BCKDK rescue experiments in iPS-derived dopaminergic neurons\",\n      \"journal\": \"Acta neuropathologica communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding partner identified by Co-IP, functional rescue in patient-derived neurons; single lab\",\n      \"pmids\": [\"39709505\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Nuclear-localized BCKDK phosphorylates RNF8 at Ser157, preventing ubiquitin-mediated degradation of RAD51 and thereby facilitating homologous recombination repair of DNA damage in breast cancer cells, independent of BCKDK's metabolic function.\",\n      \"method\": \"Subcellular fractionation showing nuclear BCKDK, co-immunoprecipitation, kinase assay, site-directed mutagenesis, RAD51 ubiquitination assay, DNA damage repair assays\",\n      \"journal\": \"Advanced science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — nuclear localization demonstrated by fractionation, phosphorylation site mapped with mutagenesis, functional HRR readout; single lab\",\n      \"pmids\": [\"40298908\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BCKDK interacts with glucose-6-phosphate dehydrogenase (G6PD), stabilizing it and increasing flux through the pentose phosphate pathway for macromolecule synthesis and ROS detoxification in triple-negative breast cancer.\",\n      \"method\": \"Co-immunoprecipitation, mass spectrometry, isotope tracer studies (13C), immunofluorescence, rescue with forced G6PD expression\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — interaction confirmed by Co-IP/MS and isotope tracing with functional rescue; single lab\",\n      \"pmids\": [\"39025830\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"PSMD14 (a deubiquitinase) directly interacts with BCKDK and deubiquitinates it, antagonizing TRIM21-mediated proteasomal degradation and stabilizing BCKDK protein levels in glioblastoma.\",\n      \"method\": \"Co-immunoprecipitation, deubiquitination assay, PSMD14 knockdown with BCKDK protein level measurement\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct deubiquitinase activity on BCKDK demonstrated, antagonism with TRIM21 established; single lab\",\n      \"pmids\": [\"41876842\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"BCKDK interacts with and phosphorylates BCLAF1 at serine 285, facilitating BCLAF1 binding to the MYC promoter, enhancing MYC transcription, upregulating hexokinase 2, and promoting aerobic glycolysis and Trametinib resistance in lung cancer.\",\n      \"method\": \"Co-immunoprecipitation, phosphorylation assay, chromatin immunoprecipitation (ChIP) showing BCLAF1 at MYC promoter, BCKDK knockdown/overexpression with downstream pathway analysis\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphorylation and transcriptional mechanism supported by Co-IP, ChIP, and functional experiments; single lab\",\n      \"pmids\": [\"40442441\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"In zebrafish, Bckdk phosphorylates the chromatin remodeling factor Phf10/Baf45a; loss of Bckdk reduces Phf10 phosphorylation, leading to epiboly defects, zygotic genome activation deregulation, and impaired miR-430 processing during the maternal-to-zygotic transition.\",\n      \"method\": \"CRISPR-RfxCas13d maternal mRNA knockdown screen, phospho-proteomics, phf10 knockdown epistasis, rescue with phospho-mimetic Phf10 mutant\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — substrate identified by phospho-proteomics, genetic epistasis confirmed, rescue with phospho-mimetic mutant; multiple orthogonal methods\",\n      \"pmids\": [\"41254269\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PRSS55 (serine protease 55) interacts with BCKDK and its substrate BCKDHA in mouse testes and sperm mitochondria, regulating BCAA metabolism and mitochondrial energy homeostasis to facilitate sperm function.\",\n      \"method\": \"LC-MS/MS proteomics and co-immunoprecipitation validating PRSS55–BCKDK and PRSS55–BCKDHA interactions; metabolomics showing BCAA accumulation in Prss55-/- testes\",\n      \"journal\": \"Cell & bioscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP and proteomics in single lab; functional connection via metabolomics in KO model\",\n      \"pmids\": [\"41444608\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"BCKDK deficiency in patient fibroblasts causes increased superoxide anion production, reduced ATP-linked respiration, and mitochondrial hyperfusion associated with changes in OPA1 and MFN2, demonstrating that BCKDK activity is required for normal mitochondrial bioenergetics and dynamics.\",\n      \"method\": \"Oxygen consumption rate measurement, ATP quantification, ROS assay, electron microscopy ultrastructure analysis, BCKDK knockdown in control fibroblasts recapitulating phenotypes\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple bioenergetic parameters measured with genetic knockdown recapitulation; single lab\",\n      \"pmids\": [\"26809120\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"BCKDK is a mitochondria-associated serine/threonine kinase that primarily phosphorylates and inactivates the E1α subunit of the branched-chain α-keto acid dehydrogenase complex (BCKDH) to restrain BCAA catabolism; beyond this canonical metabolic role, BCKDK also phosphorylates non-metabolic substrates including MEK, RNF8, BCLAF1, BCAT1, STUB1, and Phf10/Baf45a, interacts with mitochondrial Complex I subunit NDUFS1 to stabilize respiratory chain function, localizes to the nucleus to facilitate homologous recombination repair, and is itself regulated by upstream kinases (Src at Y246, Fyn at Y151) and ubiquitin ligases (TRIM21, UBE3B) that control its stability and activity.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"BCKDK is a mitochondria-associated serine/threonine kinase that controls branched-chain amino acid (BCAA) catabolism by phosphorylating and inactivating the E1α subunit of the branched-chain α-keto acid dehydrogenase complex (BCKDH), and also phosphorylates the pyruvate dehydrogenase complex when canonical PDK kinases are absent [PMID:24449431, PMID:33773101]. Beyond metabolic regulation, BCKDK phosphorylates diverse non-metabolic substrates—including MEK, BCAT1, STUB1, RNF8, BCLAF1, and the chromatin remodeling factor Phf10/Baf45a—thereby engaging MAPK/ERK signaling, DNA homologous recombination repair, MYC-driven glycolysis, and zygotic genome activation [PMID:28501528, PMID:38621458, PMID:40298908, PMID:40442441, PMID:41254269]. BCKDK activity and stability are regulated by upstream tyrosine kinases Src (at Y246) and Fyn (at Y151) and by opposing ubiquitin-mediated turnover through TRIM21 and the deubiquitinase PSMD14, while the E3 ligase UBE3B also targets BCKDK as an in vivo substrate [PMID:32238881, PMID:39170503, PMID:41876842, PMID:30808755]. Loss-of-function mutations in BCKDK cause a Mendelian disorder characterized by reduced plasma BCAAs with increased BCKDH activity, and BCKDK deficiency additionally disrupts mitochondrial Complex I stability, bioenergetics, and dynamics [PMID:24449431, PMID:26809120, PMID:39709505].\",\n  \"teleology\": [\n    {\n      \"year\": 2014,\n      \"claim\": \"Establishing the core enzymatic function: patient loss-of-function mutations demonstrated that BCKDK is the kinase responsible for phosphorylating and inactivating BCKDH-E1α, defining its role as the master negative regulator of BCAA catabolism.\",\n      \"evidence\": \"Biochemical analysis of patient-derived fibroblasts with BCKDK mutations showing undetectable phospho-E1α and increased BCKD activity\",\n      \"pmids\": [\"24449431\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for E1α recognition not resolved\", \"Whether BCKDK has additional mitochondrial substrates was unknown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"BCKDK deficiency was shown to impair mitochondrial bioenergetics and dynamics, revealing that the kinase's function extends beyond substrate-level metabolic regulation to maintenance of respiratory chain function and mitochondrial morphology.\",\n      \"evidence\": \"Oxygen consumption, ATP, ROS, and electron microscopy in BCKDK-deficient patient fibroblasts with knockdown recapitulation\",\n      \"pmids\": [\"26809120\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct mitochondrial target(s) mediating bioenergetic and morphological changes were not identified\", \"Whether the effect is secondary to BCAA imbalance was not excluded\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"The discovery that BCKDK directly phosphorylates MEK to activate ERK signaling in colorectal cancer established the first non-metabolic substrate and linked BCKDK to oncogenic MAPK pathway activation.\",\n      \"evidence\": \"Co-immunoprecipitation, MEK phosphorylation western blot, and cell transformation assays with pharmacological inhibition\",\n      \"pmids\": [\"28501528\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific MEK phosphorylation site not mapped\", \"Independence from BCAA effects inferred but not fully dissected genetically\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identification of BCKDK as an in vivo substrate of the E3 ligase UBE3B revealed that BCKDK protein levels are controlled by ubiquitin-dependent degradation, connecting its regulation to Kaufman oculocerebrofacial syndrome-associated metabolic perturbations.\",\n      \"evidence\": \"Proteomics-based substrate identification and metabolomic profiling in Ube3b-knockout mice\",\n      \"pmids\": [\"30808755\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific ubiquitination sites on BCKDK by UBE3B not mapped\", \"Functional consequence of UBE3B loss on BCKDK activity not directly measured\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Src and APN-mediated phosphorylation of BCKDK at Y246 and S31, respectively, established that BCKDK is itself subject to upstream kinase regulation that modulates both its catalytic activity and its engagement with ERK signaling.\",\n      \"evidence\": \"In vitro kinase assays, phosphoproteomics, Src-KO validation, point mutation analysis, and proximity ligation assay\",\n      \"pmids\": [\"32238881\", \"32457292\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Y246 and S31 phosphorylation are coordinated or independent events is unknown\", \"The phosphatase(s) opposing these modifications are unidentified\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Genetic epistasis in mice revealed BCKDK as a compensatory kinase for the pyruvate dehydrogenase complex (PDC) when all four PDK isoforms are absent, demonstrating substrate promiscuity with developmental significance.\",\n      \"evidence\": \"Sequential Pdk1-4 knockout combined with Bckdk knockout in mice; PDC phosphorylation and metabolic flux analysis\",\n      \"pmids\": [\"33773101\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether BCKDK phosphorylates PDC under physiological conditions with PDKs present is unclear\", \"Specific PDC subunit phosphorylation sites targeted by BCKDK not fully resolved\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"BCKDK silencing reduced mitochondrial electron transport chain protein expression, oxygen consumption, and mTORC1 signaling in breast cancer cells, reinforcing a broader role in mitochondrial and growth-regulatory homeostasis beyond BCAA catabolism.\",\n      \"evidence\": \"Genetic knockdown and pharmacological inhibition with transcriptomics, OCR, and mTORC1 pathway readouts in TNBC cells\",\n      \"pmids\": [\"34526485\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct versus indirect effects on ETC complex expression not distinguished\", \"Whether sestrin 2 upregulation is a direct phosphorylation target or transcriptional response is unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"BCKDK was shown to phosphorylate both BCAT1 (enhancing its activity) and STUB1 (disrupting BCAT1 ubiquitination), revealing a dual mechanism of substrate stabilization through direct phosphorylation and E3 ligase interference.\",\n      \"evidence\": \"In vitro kinase assays, mass spectrometry-based site mapping, point mutation analysis, and in vivo tumor models\",\n      \"pmids\": [\"38621458\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the BCAT1-stabilizing mechanism operates outside glioblastoma contexts is untested\", \"Crystal structure of BCKDK–BCAT1 interaction lacking\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"BCKDK was found to stabilize talin1 by blocking TRIM21-mediated ubiquitination, linking BCKDK to integrin-associated FAK/MAPK signaling and cell migration—expanding its non-catalytic scaffolding functions.\",\n      \"evidence\": \"Co-immunoprecipitation, ubiquitination assays, migration assays in vitro and lung metastasis in vivo\",\n      \"pmids\": [\"37460470\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether BCKDK directly phosphorylates talin1 or acts purely as a competitive binding partner for TRIM21 is unresolved\", \"Single-lab finding without independent replication\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Multiple studies expanded the BCKDK substrate repertoire and regulatory network: Fyn phosphorylates BCKDK at Y151 in glioblastoma; BCKDK interacts with and stabilizes NDUFS1 of Complex I to maintain mitochondrial membrane potential; nuclear BCKDK phosphorylates RNF8 to facilitate homologous recombination repair; BCKDK stabilizes G6PD to promote the pentose phosphate pathway; PSMD14 deubiquitinates BCKDK opposing TRIM21; and BCKDK phosphorylates BCLAF1 to activate MYC transcription.\",\n      \"evidence\": \"Kinase assays, Co-IP, subcellular fractionation, ChIP, isotope tracing, deubiquitination assays, iPSC-derived neuron models, and tumor models across multiple independent studies\",\n      \"pmids\": [\"39170503\", \"39709505\", \"40298908\", \"39025830\", \"41876842\", \"40442441\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Most non-metabolic substrates identified in single labs without independent replication\", \"Structural basis for BCKDK's nuclear localization signal not identified\", \"Relative physiological importance of metabolic versus non-metabolic BCKDK functions is unranked\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"BCKDK was shown to phosphorylate the chromatin remodeling factor Phf10/Baf45a in zebrafish, establishing an essential role during the maternal-to-zygotic transition through regulation of zygotic genome activation and miR-430 processing.\",\n      \"evidence\": \"CRISPR-RfxCas13d maternal knockdown screen, phospho-proteomics, genetic epistasis, and phospho-mimetic rescue in zebrafish embryos\",\n      \"pmids\": [\"41254269\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the BCKDK–Phf10 axis is conserved in mammals is unknown\", \"Mechanism by which Phf10 phosphorylation controls miR-430 processing not fully elucidated\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"A unifying structural and systems-level understanding of how BCKDK achieves substrate selectivity across its diverse metabolic and non-metabolic targets, and how its mitochondrial, cytoplasmic, and nuclear pools are differentially regulated, remains to be established.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal or cryo-EM structure of full-length BCKDK bound to non-BCKDH substrates\", \"Relative contribution of BCKDK kinase activity versus scaffolding to each phenotype not systematically tested\", \"How BCKDK is partitioned among subcellular compartments is mechanistically unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3, 5, 7, 9, 11, 14, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 10, 16, 17]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2, 5, 6, 12, 16]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 4, 9, 14]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [11]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [7, 8, 13]}\n    ],\n    \"complexes\": [\n      \"BCKDH complex (as regulatory kinase)\"\n    ],\n    \"partners\": [\n      \"BCKDHA\",\n      \"MEK\",\n      \"NDUFS1\",\n      \"BCAT1\",\n      \"STUB1\",\n      \"RNF8\",\n      \"BCLAF1\",\n      \"G6PD\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}