{"gene":"COQ8A","run_date":"2026-06-09T22:57:19","timeline":{"discoveries":[{"year":2008,"finding":"ADCK3 (COQ8A) is a mitochondrial protein homologous to yeast COQ8 and bacterial UbiB proteins required for CoQ biosynthesis; missense mutations introduced at corresponding yeast COQ8 positions caused respiratory phenotype and severely reduced ubiquinone synthesis, demonstrating these mutations alter protein function in CoQ biosynthesis.","method":"Yeast complementation assay, growth on nonfermentable carbon source, ubiquinone synthesis measurement","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — functional rescue assay in yeast with direct biochemical readout (ubiquinone synthesis), replicated across two independent papers (PMID:18319074 and PMID:18319072) with multiple mutations tested","pmids":["18319074","18319072"],"is_preprint":false},{"year":2008,"finding":"ADCK3 belongs to the family of atypical kinases (including phosphoinositide and choline kinases), suggesting it plays an indirect regulatory role in ubiquinone biosynthesis possibly as part of a feedback loop regulating ATP production.","method":"Phylogenetic analysis","journal":"American journal of human genetics","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational/phylogenetic inference only, no direct experimental confirmation of kinase activity or regulatory role in this paper","pmids":["18319074"],"is_preprint":false},{"year":2011,"finding":"Human ADCK3 (with a yeast mitochondrial leader sequence) rescues growth of yeast coq8 null mutants on nonfermentable carbon source and partially restores Q6 biosynthesis; furthermore, Coq3p, Coq5p, and Coq7p are phosphorylated in a Coq8p-dependent manner, indicating ADCK3 functions as a protein kinase that phosphorylates CoQ biosynthetic complex components.","method":"Yeast complementation, two-dimensional gel phosphorylation analysis, ubiquinone biosynthesis measurement","journal":"Biochimica et biophysica acta","confidence":"High","confidence_rationale":"Tier 1–2 / Strong — direct functional rescue with biochemical readouts (CoQ synthesis, phosphorylation state of multiple substrates), multiple orthogonal methods in one study","pmids":["21296186"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of ADCK3 reveals it employs an atypical protein kinase-like fold with multiple UbiB-specific features that inhibit canonical protein kinase activity: an N-terminal domain occupies the typical substrate binding pocket, and a unique A-rich loop limits ATP binding by establishing unusual selectivity for ADP over ATP. A single alanine-to-glycine mutation in the A-rich loop flips coenzyme selectivity to enable autophosphorylation but inhibits CoQ biosynthesis in vivo, demonstrating the functional relevance of ADP selectivity for CoQ production.","method":"X-ray crystallography, site-directed mutagenesis, in vivo CoQ biosynthesis assay, biochemical coenzyme selectivity assay","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure combined with mutagenesis and in vivo functional validation with multiple orthogonal methods in single rigorous study","pmids":["25498144"],"is_preprint":false},{"year":2014,"finding":"The transmembrane helix of ADCK3 homodimerizes via an extended Gly-zipper motif, as predicted computationally and validated experimentally; this transmembrane domain oligomerization is proposed to regulate ADCK3 biological activity.","method":"Computational modeling of transmembrane helix interactions, experimental validation of oligomerization (transmembrane helix association assay)","journal":"Journal of the American Chemical Society","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — computational prediction validated by experimental oligomerization assay, but functional consequence of dimerization was not directly demonstrated","pmids":["25216398"],"is_preprint":false},{"year":2014,"finding":"Human ADCK3 kinase domain exhibits Mg2+-dependent ATPase activity when expressed as a maltose-binding protein fusion in E. coli, providing direct biochemical evidence for its function as an atypical kinase.","method":"Recombinant protein expression, in vitro ATPase activity assay","journal":"Protein expression and purification","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro enzymatic assay demonstrating ATPase activity, but single lab, single method, no mutagenesis validation","pmids":["25540914"],"is_preprint":false},{"year":2016,"finding":"ADCK3 localizes to mitochondrial cristae via an N-terminal localization signal; ADCK3 deficiency decreases cellular CoQ10 content; endogenous ADCK3 associates in vitro with recombinant Coq3, Coq5, Coq7, and Coq9 (components of the CoQ10 biosynthetic machinery).","method":"Subcellular fractionation/immunofluorescence for localization, CoQ10 quantification, in vitro pulldown with recombinant proteins","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — direct localization experiment with functional consequence (CoQ10 loss), plus in vitro pulldown with multiple CoQ biosynthesis components; single lab","pmids":["26866375"],"is_preprint":false},{"year":2022,"finding":"The small molecule 2-propylphenol (a CoQ precursor mimetic) binds COQ8A at an identified site and allosterically modulates a conserved COQ8A domain to increase nucleotide affinity and ATPase activity, revealing a mechanism by which CoQ precursor lipids regulate COQ8A enzymatic function.","method":"NMR, hydrogen-deuterium exchange mass spectrometry, ATPase activity assay","journal":"ACS chemical biology","confidence":"Medium","confidence_rationale":"Tier 1–2 / Moderate — multiple orthogonal biophysical methods (NMR + HDX-MS) combined with enzymatic assay, single lab","pmids":["35904798"],"is_preprint":false},{"year":2023,"finding":"Conditional Purkinje-neuron-specific knockout of COQ8A demonstrates that loss of COQ8A specifically in Purkinje neurons is the main cause of cerebellar ataxia; COQ8A-depleted Purkinje neurons exhibit abnormal dendritic arborizations, altered mitochondrial function, and intracellular calcium dysregulation; oxidative phosphorylation (particularly Complex IV) is primarily altered at presymptomatic stages.","method":"Purkinje-specific conditional knockout mouse, behavioral/motor testing, in vivo and in vitro morphological analysis, mitochondrial function assays, calcium imaging","journal":"Brain : a journal of neurology","confidence":"High","confidence_rationale":"Tier 2 / Strong — cell-type-specific conditional knockout with multiple orthogonal functional readouts (morphology, mitochondrial function, calcium dynamics) establishing cell-autonomous role","pmids":["36960552"],"is_preprint":false},{"year":2023,"finding":"ADCK3 is a direct transcriptional target of tumor suppressor p53 in endometrial carcinoma cells; loss of ADCK3 suppresses MPA-mediated ferroptosis by abrogating ALOX15 transcriptional activation, placing ADCK3 downstream of p53 and upstream of ALOX15 in a ferroptosis pathway.","method":"Genome-wide CRISPR screen, ChIP-qPCR, luciferase reporter assay, western blotting, RT-qPCR","journal":"British journal of cancer","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — CRISPR screen plus ChIP-qPCR and reporter assay establishing p53-ADCK3-ALOX15 axis; single lab, cancer-specific context","pmids":["37402867"],"is_preprint":false},{"year":2025,"finding":"The COQ8A E548K (equivalent to human E551K) knock-in mutation in mice leads to variable instability of the COQ8A E548K protein and reduced expression of COQ5 and COQ7 in cerebellum and muscle (similar to constitutive knockout), demonstrating that COQ8A is required for maintaining protein levels of other CoQ biosynthesis pathway components; however, mitochondrial function and tissue architecture remained intact in the knock-in model.","method":"Knock-in mouse model, western blotting of CoQ pathway proteins, mitochondrial function assays, behavioral testing","journal":"bioRxiv","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo knock-in model with biochemical validation of pathway protein levels; preprint, not peer-reviewed","pmids":["bio_10.1101_2025.04.23.650169"],"is_preprint":true}],"current_model":"COQ8A (ADCK3) is a mitochondrial atypical kinase-like protein that localizes to mitochondrial cristae via an N-terminal signal and adopts a unique UbiB-family fold with ADP (rather than ATP) selectivity; it is required for coenzyme Q10 (CoQ10) biosynthesis by phosphorylating CoQ biosynthetic complex components (Coq3, Coq5, Coq7) and maintaining the protein stability of other CoQ pathway enzymes (COQ5, COQ7), with its enzymatic activity allosterically stimulated by CoQ precursor lipids; in Purkinje neurons, COQ8A loss causes mitochondrial dysfunction (primarily Complex IV), calcium dysregulation, and dendritic morphological defects that underlie cerebellar ataxia, and in cancer cells COQ8A acts as a p53 transcriptional target that promotes ferroptosis via ALOX15."},"narrative":{"mechanistic_narrative":"COQ8A (ADCK3) is a mitochondrial UbiB-family atypical kinase-like protein required for coenzyme Q (CoQ10) biosynthesis, functioning as a regulatory hub for the CoQ biosynthetic machinery [PMID:18319074, PMID:18319072, PMID:21296186]. It localizes to mitochondrial cristae via an N-terminal signal, where it associates with the CoQ10 biosynthetic complex components Coq3, Coq5, Coq7, and Coq9, and its deficiency reduces cellular CoQ10 content [PMID:26866375]. COQ8A promotes phosphorylation of Coq3, Coq5, and Coq7 in a Coq8-dependent manner and maintains the protein stability of CoQ pathway enzymes including COQ5 and COQ7 [PMID:21296186, PMID:bio_10.1101_2025.04.23.650169]. Structurally, it adopts an atypical protein kinase-like fold whose UbiB-specific features—an N-terminal domain occupying the substrate pocket and an A-rich loop—confer unusual selectivity for ADP over ATP that is essential for CoQ production in vivo, while the kinase domain exhibits Mg2+-dependent ATPase activity [PMID:25498144, PMID:25540914]. Its enzymatic activity is allosterically stimulated by CoQ precursor lipids: a precursor mimetic binds a conserved domain to increase nucleotide affinity and ATPase activity, establishing feedback regulation by pathway intermediates [PMID:35904798]. In Purkinje neurons, cell-autonomous loss of COQ8A causes mitochondrial dysfunction (primarily Complex IV), intracellular calcium dysregulation, and abnormal dendritic arborization that underlie cerebellar ataxia [PMID:36960552]. Separately, in endometrial carcinoma cells COQ8A acts as a direct p53 transcriptional target that promotes ferroptosis through transcriptional activation of ALOX15 [PMID:37402867].","teleology":[{"year":2008,"claim":"Established that the human gene is a functional ortholog of yeast COQ8/bacterial UbiB required for CoQ biosynthesis, mapping disease-relevant missense changes onto a defined biosynthetic role.","evidence":"Yeast complementation and ubiquinone synthesis measurement with mutations introduced at conserved positions","pmids":["18319074","18319072"],"confidence":"High","gaps":["Did not define the direct biochemical activity of the human protein","Did not identify physical substrates or partners","Phylogenetic classification as an atypical kinase was inference only"]},{"year":2011,"claim":"Resolved whether ADCK3 acts directly on the CoQ machinery by showing Coq3, Coq5, and Coq7 are phosphorylated in a Coq8-dependent manner, framing it as a protein kinase for the biosynthetic complex.","evidence":"Yeast complementation with human ADCK3 plus two-dimensional gel phosphorylation analysis of Coq substrates","pmids":["21296186"],"confidence":"High","gaps":["Did not show ADCK3 directly phosphorylates these substrates in vitro","Did not exclude an indirect/scaffolding contribution to phosphorylation"]},{"year":2014,"claim":"Explained the paradox of CoQ-essential but canonical-kinase-dead behavior by solving the structure and demonstrating UbiB-specific features that enforce ADP-over-ATP selectivity required for CoQ production.","evidence":"X-ray crystallography with A-rich loop mutagenesis and in vivo CoQ biosynthesis assays; companion biochemical ATPase assay of the recombinant kinase domain","pmids":["25498144","25540914"],"confidence":"High","gaps":["Physiological phosphoacceptor and catalytic output remained undefined","ATPase activity demonstrated without mutagenesis validation in the in vitro study"]},{"year":2014,"claim":"Identified a structural basis for higher-order assembly by showing the transmembrane helix homodimerizes via a Gly-zipper motif, implicating oligomerization in activity regulation.","evidence":"Computational transmembrane helix modeling validated by an experimental oligomerization assay","pmids":["25216398"],"confidence":"Medium","gaps":["Functional consequence of dimerization not directly demonstrated","Oligomeric state of full-length protein in mitochondria not established"]},{"year":2016,"claim":"Localized the protein to mitochondrial cristae and tied its physical association with multiple CoQ biosynthetic components to a functional CoQ10 deficiency.","evidence":"Subcellular fractionation/immunofluorescence, CoQ10 quantification, and in vitro pulldown with recombinant Coq3/Coq5/Coq7/Coq9","pmids":["26866375"],"confidence":"Medium","gaps":["Interactions shown in vitro with recombinant proteins, not endogenous complex stoichiometry","Single lab without reciprocal validation"]},{"year":2022,"claim":"Defined how the pathway feeds back on the enzyme by mapping a CoQ-precursor-mimetic binding site that allosterically raises nucleotide affinity and ATPase activity.","evidence":"NMR and hydrogen-deuterium exchange mass spectrometry with ATPase activity assay using 2-propylphenol","pmids":["35904798"],"confidence":"Medium","gaps":["Endogenous lipid ligand and physiological concentration range not established","Link between allosteric activation and substrate phosphorylation not shown"]},{"year":2023,"claim":"Established cell-autonomous causation of cerebellar ataxia by showing Purkinje-neuron-specific loss drives the disease through mitochondrial (Complex IV) dysfunction, calcium dysregulation, and dendritic defects.","evidence":"Purkinje-specific conditional knockout mouse with behavioral, morphological, mitochondrial, and calcium-imaging readouts","pmids":["36960552"],"confidence":"High","gaps":["Mechanistic chain from CoQ loss to Complex IV and calcium phenotypes not fully resolved","Whether dendritic defects are primary or secondary to bioenergetic failure unresolved"]},{"year":2023,"claim":"Placed COQ8A in a tumor-suppressor signaling axis, identifying it as a direct p53 target that promotes ferroptosis via ALOX15 in endometrial carcinoma.","evidence":"Genome-wide CRISPR screen, ChIP-qPCR, luciferase reporter, RT-qPCR and western blotting","pmids":["37402867"],"confidence":"Medium","gaps":["Mechanistic link between COQ8A's mitochondrial CoQ role and ALOX15 transcription not defined","Single lab in a cancer-specific context"]},{"year":2025,"claim":"Tested a patient-equivalent point mutant in vivo, showing E548K destabilizes COQ8A and lowers COQ5/COQ7 levels, confirming a chaperone-like stabilization role distinct from overt mitochondrial failure.","evidence":"Knock-in mouse with western blotting of CoQ pathway proteins, mitochondrial assays, and behavioral testing (preprint)","pmids":["bio_10.1101_2025.04.23.650169"],"confidence":"Medium","gaps":["Preprint, not peer-reviewed","Why mitochondrial function and tissue architecture remained intact despite reduced pathway proteins is unexplained"]},{"year":null,"claim":"The direct in vitro phosphorylation reaction—whether COQ8A itself catalyzes phosphoryl transfer to a defined acceptor or acts primarily as an ADP-selective stabilizing scaffold—remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No reconstituted kinase reaction with an identified physiological substrate","Mechanistic unification of phosphorylation, protein stabilization, and ATPase activities is lacking"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[5,7]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[3,5]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,6]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,2,6]}],"complexes":[],"partners":["COQ3","COQ5","COQ7","COQ9"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8NI60","full_name":"Atypical kinase COQ8A, mitochondrial","aliases":["Chaperone activity of bc1 complex-like","Chaperone-ABC1-like","Coenzyme Q protein 8A","aarF domain-containing protein kinase 3"],"length_aa":647,"mass_kda":72.0,"function":"Atypical kinase involved in the biosynthesis of coenzyme Q, also named ubiquinone, an essential lipid-soluble electron transporter for aerobic cellular respiration (PubMed:21296186, PubMed:25498144, PubMed:25540914, PubMed:27499294, PubMed:36302899, PubMed:38425362). Its substrate specificity is still unclear: may act as a protein kinase that mediates phosphorylation of COQ3 (By similarity). According to other reports, acts as a small molecule kinase, possibly a lipid kinase that phosphorylates a prenyl lipid in the ubiquinone biosynthesis pathway, as suggested by its ability to bind coenzyme Q lipid intermediates (PubMed:25498144, PubMed:27499294). However, the small molecule kinase activity was not confirmed by another publication (By similarity). Shows an unusual selectivity for binding ADP over ATP (PubMed:25498144)","subcellular_location":"Mitochondrion membrane","url":"https://www.uniprot.org/uniprotkb/Q8NI60/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/COQ8A","classification":"Not Classified","n_dependent_lines":4,"n_total_lines":1208,"dependency_fraction":0.0033112582781456954},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/COQ8A","total_profiled":1310},"omim":[{"mim_id":"612016","title":"COENZYME Q10 DEFICIENCY, PRIMARY, 4; COQ10D4","url":"https://www.omim.org/entry/612016"},{"mim_id":"606980","title":"COENZYME Q8A; COQ8A","url":"https://www.omim.org/entry/606980"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mitochondria","reliability":"Supported"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"skeletal muscle","ntpm":1091.3},{"tissue":"tongue","ntpm":452.9}],"url":"https://www.proteinatlas.org/search/COQ8A"},"hgnc":{"alias_symbol":["COQ8","SCAR9"],"prev_symbol":["CABC1","ADCK3"]},"alphafold":{"accession":"Q8NI60","domains":[{"cath_id":"-","chopping":"196-234_254-305_368-404","consensus_level":"medium","plddt":70.9071,"start":196,"end":404},{"cath_id":"3.30.200.20","chopping":"309-361_408-448","consensus_level":"medium","plddt":93.9049,"start":309,"end":448},{"cath_id":"-","chopping":"452-647","consensus_level":"medium","plddt":86.9093,"start":452,"end":647}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NI60","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NI60-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8NI60-F1-predicted_aligned_error_v6.png","plddt_mean":69.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=COQ8A","jax_strain_url":"https://www.jax.org/strain/search?query=COQ8A"},"sequence":{"accession":"Q8NI60","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8NI60.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8NI60/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8NI60"}},"corpus_meta":[{"pmid":"18319074","id":"PMC_18319074","title":"ADCK3, an ancestral kinase, is mutated in a form of recessive ataxia associated with coenzyme Q10 deficiency.","date":"2008","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18319074","citation_count":243,"is_preprint":false},{"pmid":"18319072","id":"PMC_18319072","title":"CABC1 gene mutations cause ubiquinone deficiency with cerebellar ataxia and seizures.","date":"2008","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/18319072","citation_count":217,"is_preprint":false},{"pmid":"25498144","id":"PMC_25498144","title":"Mitochondrial ADCK3 employs an atypical protein kinase-like fold to enable coenzyme Q biosynthesis.","date":"2014","source":"Molecular cell","url":"https://pubmed.ncbi.nlm.nih.gov/25498144","citation_count":100,"is_preprint":false},{"pmid":"21296186","id":"PMC_21296186","title":"Expression of the human atypical kinase ADCK3 rescues coenzyme Q biosynthesis and phosphorylation of Coq polypeptides in yeast coq8 mutants.","date":"2011","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/21296186","citation_count":96,"is_preprint":false},{"pmid":"22036850","id":"PMC_22036850","title":"Adult-onset cerebellar ataxia due to mutations in CABC1/ADCK3.","date":"2011","source":"Journal of neurology, neurosurgery, and psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/22036850","citation_count":86,"is_preprint":false},{"pmid":"32337771","id":"PMC_32337771","title":"Clinico-Genetic, Imaging and Molecular Delineation of COQ8A-Ataxia: A Multicenter Study of 59 Patients.","date":"2020","source":"Annals of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/32337771","citation_count":64,"is_preprint":false},{"pmid":"20580948","id":"PMC_20580948","title":"Nonsense mutations in CABC1/ADCK3 cause progressive cerebellar ataxia and atrophy.","date":"2010","source":"Mitochondrion","url":"https://pubmed.ncbi.nlm.nih.gov/20580948","citation_count":60,"is_preprint":false},{"pmid":"11888884","id":"PMC_11888884","title":"Isolation of a novel gene, CABC1, encoding a mitochondrial protein that is highly homologous to yeast activity of bc1 complex.","date":"2002","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/11888884","citation_count":44,"is_preprint":false},{"pmid":"24218524","id":"PMC_24218524","title":"Autosomal-recessive cerebellar ataxia caused by a novel ADCK3 mutation that elongates the protein: clinical, genetic and biochemical characterisation.","date":"2013","source":"Journal of neurology, neurosurgery, and psychiatry","url":"https://pubmed.ncbi.nlm.nih.gov/24218524","citation_count":41,"is_preprint":false},{"pmid":"26818466","id":"PMC_26818466","title":"Cerebellar ataxia and severe muscle CoQ10 deficiency in a patient with a novel mutation in ADCK3.","date":"2016","source":"Clinical 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cancer","url":"https://pubmed.ncbi.nlm.nih.gov/37402867","citation_count":9,"is_preprint":false},{"pmid":"35275351","id":"PMC_35275351","title":"Epilepsia Partialis Continua a Clinical Feature of a Missense Variant in the ADCK3 Gene and Poor Response to Therapy.","date":"2022","source":"Journal of molecular neuroscience : MN","url":"https://pubmed.ncbi.nlm.nih.gov/35275351","citation_count":9,"is_preprint":false},{"pmid":"33622667","id":"PMC_33622667","title":"Photoparoxysmal response in ADCK3 autosomal recessive ataxia: a case report and literature review.","date":"2021","source":"Epileptic disorders : international epilepsy journal with videotape","url":"https://pubmed.ncbi.nlm.nih.gov/33622667","citation_count":8,"is_preprint":false},{"pmid":"37476682","id":"PMC_37476682","title":"Adolescence Onset Primary Coenzyme Q10 Deficiency With Rare CoQ8A Gene Mutation: A Case Report and Review of Literature.","date":"2023","source":"Clinical medicine insights. Case reports","url":"https://pubmed.ncbi.nlm.nih.gov/37476682","citation_count":7,"is_preprint":false},{"pmid":"31078656","id":"PMC_31078656","title":"Exome sequencing found a novel homozygous deletion in ADCK3 gene involved in autosomal recessive spinocerebellar ataxia.","date":"2019","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/31078656","citation_count":7,"is_preprint":false},{"pmid":"35757998","id":"PMC_35757998","title":"Primary CoQ10 deficiency with a severe phenotype due to the c.901 C > T (p.R301W) mutation in the COQ8A gene.","date":"2022","source":"The International journal of neuroscience","url":"https://pubmed.ncbi.nlm.nih.gov/35757998","citation_count":6,"is_preprint":false},{"pmid":"32553579","id":"PMC_32553579","title":"A novel COQ8A missense variant associated with a mild form of primary coenzyme Q10 deficiency type 4.","date":"2020","source":"Clinical biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/32553579","citation_count":6,"is_preprint":false},{"pmid":"38229639","id":"PMC_38229639","title":"Stroke-Like Episodes and Epilepsy in a Patient with COQ8A-Related Coenzyme Q10 Deficiency.","date":"2023","source":"Annals of Indian Academy of Neurology","url":"https://pubmed.ncbi.nlm.nih.gov/38229639","citation_count":4,"is_preprint":false},{"pmid":"27442024","id":"PMC_27442024","title":"Correction: AarF Domain Containing Kinase 3 (ADCK3) Mutant Cells Display Signs of Oxidative Stress, Defects in Mitochondrial Homeostasis and Lysosomal Accumulation.","date":"2016","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/27442024","citation_count":4,"is_preprint":false},{"pmid":"38429489","id":"PMC_38429489","title":"Mitochondrial Dysfunction due to Novel COQ8A Variation with Poor Response to CoQ10 Treatment: A Comprehensive Study and Review of Literatures.","date":"2024","source":"Cerebellum (London, England)","url":"https://pubmed.ncbi.nlm.nih.gov/38429489","citation_count":3,"is_preprint":false},{"pmid":"35904798","id":"PMC_35904798","title":"2-Propylphenol Allosterically Modulates COQ8A to Enhance ATPase Activity.","date":"2022","source":"ACS chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/35904798","citation_count":2,"is_preprint":false},{"pmid":"39025788","id":"PMC_39025788","title":"Identification of Potent ADCK3 Inhibitors through Structure-Based Virtual Screening.","date":"2024","source":"Journal of chemical information and modeling","url":"https://pubmed.ncbi.nlm.nih.gov/39025788","citation_count":1,"is_preprint":false},{"pmid":"41992454","id":"PMC_41992454","title":"COQ8A-related Primary Coenzyme Q10 Deficiency Mimicking Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Syndrome: A Pediatric Case Report and Review of Mitochondrial Mimics.","date":"2026","source":"Annals of African medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41992454","citation_count":0,"is_preprint":false},{"pmid":"41568333","id":"PMC_41568333","title":"Case Report: Myoclonic and tremulous movements associated with COQ8A-related coenzyme Q10 deficiency type 4.","date":"2026","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/41568333","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.04.23.650169","title":"Characterization of a COQ8A-ataxia mouse model with E548K single-site mutation: distinct and comparable findings relative to a loss-of-function mutation","date":"2025-04-23","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.23.650169","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18595,"output_tokens":2787,"usd":0.048795,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":10210,"output_tokens":3357,"usd":0.067488,"stage2_stop_reason":"end_turn"},"total_usd":0.116283,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2008,\n      \"finding\": \"ADCK3 (COQ8A) is a mitochondrial protein homologous to yeast COQ8 and bacterial UbiB proteins required for CoQ biosynthesis; missense mutations introduced at corresponding yeast COQ8 positions caused respiratory phenotype and severely reduced ubiquinone synthesis, demonstrating these mutations alter protein function in CoQ biosynthesis.\",\n      \"method\": \"Yeast complementation assay, growth on nonfermentable carbon source, ubiquinone synthesis measurement\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — functional rescue assay in yeast with direct biochemical readout (ubiquinone synthesis), replicated across two independent papers (PMID:18319074 and PMID:18319072) with multiple mutations tested\",\n      \"pmids\": [\"18319074\", \"18319072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"ADCK3 belongs to the family of atypical kinases (including phosphoinositide and choline kinases), suggesting it plays an indirect regulatory role in ubiquinone biosynthesis possibly as part of a feedback loop regulating ATP production.\",\n      \"method\": \"Phylogenetic analysis\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational/phylogenetic inference only, no direct experimental confirmation of kinase activity or regulatory role in this paper\",\n      \"pmids\": [\"18319074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Human ADCK3 (with a yeast mitochondrial leader sequence) rescues growth of yeast coq8 null mutants on nonfermentable carbon source and partially restores Q6 biosynthesis; furthermore, Coq3p, Coq5p, and Coq7p are phosphorylated in a Coq8p-dependent manner, indicating ADCK3 functions as a protein kinase that phosphorylates CoQ biosynthetic complex components.\",\n      \"method\": \"Yeast complementation, two-dimensional gel phosphorylation analysis, ubiquinone biosynthesis measurement\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Strong — direct functional rescue with biochemical readouts (CoQ synthesis, phosphorylation state of multiple substrates), multiple orthogonal methods in one study\",\n      \"pmids\": [\"21296186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of ADCK3 reveals it employs an atypical protein kinase-like fold with multiple UbiB-specific features that inhibit canonical protein kinase activity: an N-terminal domain occupies the typical substrate binding pocket, and a unique A-rich loop limits ATP binding by establishing unusual selectivity for ADP over ATP. A single alanine-to-glycine mutation in the A-rich loop flips coenzyme selectivity to enable autophosphorylation but inhibits CoQ biosynthesis in vivo, demonstrating the functional relevance of ADP selectivity for CoQ production.\",\n      \"method\": \"X-ray crystallography, site-directed mutagenesis, in vivo CoQ biosynthesis assay, biochemical coenzyme selectivity assay\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure combined with mutagenesis and in vivo functional validation with multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"25498144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"The transmembrane helix of ADCK3 homodimerizes via an extended Gly-zipper motif, as predicted computationally and validated experimentally; this transmembrane domain oligomerization is proposed to regulate ADCK3 biological activity.\",\n      \"method\": \"Computational modeling of transmembrane helix interactions, experimental validation of oligomerization (transmembrane helix association assay)\",\n      \"journal\": \"Journal of the American Chemical Society\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — computational prediction validated by experimental oligomerization assay, but functional consequence of dimerization was not directly demonstrated\",\n      \"pmids\": [\"25216398\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Human ADCK3 kinase domain exhibits Mg2+-dependent ATPase activity when expressed as a maltose-binding protein fusion in E. coli, providing direct biochemical evidence for its function as an atypical kinase.\",\n      \"method\": \"Recombinant protein expression, in vitro ATPase activity assay\",\n      \"journal\": \"Protein expression and purification\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro enzymatic assay demonstrating ATPase activity, but single lab, single method, no mutagenesis validation\",\n      \"pmids\": [\"25540914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ADCK3 localizes to mitochondrial cristae via an N-terminal localization signal; ADCK3 deficiency decreases cellular CoQ10 content; endogenous ADCK3 associates in vitro with recombinant Coq3, Coq5, Coq7, and Coq9 (components of the CoQ10 biosynthetic machinery).\",\n      \"method\": \"Subcellular fractionation/immunofluorescence for localization, CoQ10 quantification, in vitro pulldown with recombinant proteins\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — direct localization experiment with functional consequence (CoQ10 loss), plus in vitro pulldown with multiple CoQ biosynthesis components; single lab\",\n      \"pmids\": [\"26866375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The small molecule 2-propylphenol (a CoQ precursor mimetic) binds COQ8A at an identified site and allosterically modulates a conserved COQ8A domain to increase nucleotide affinity and ATPase activity, revealing a mechanism by which CoQ precursor lipids regulate COQ8A enzymatic function.\",\n      \"method\": \"NMR, hydrogen-deuterium exchange mass spectrometry, ATPase activity assay\",\n      \"journal\": \"ACS chemical biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — multiple orthogonal biophysical methods (NMR + HDX-MS) combined with enzymatic assay, single lab\",\n      \"pmids\": [\"35904798\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Conditional Purkinje-neuron-specific knockout of COQ8A demonstrates that loss of COQ8A specifically in Purkinje neurons is the main cause of cerebellar ataxia; COQ8A-depleted Purkinje neurons exhibit abnormal dendritic arborizations, altered mitochondrial function, and intracellular calcium dysregulation; oxidative phosphorylation (particularly Complex IV) is primarily altered at presymptomatic stages.\",\n      \"method\": \"Purkinje-specific conditional knockout mouse, behavioral/motor testing, in vivo and in vitro morphological analysis, mitochondrial function assays, calcium imaging\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — cell-type-specific conditional knockout with multiple orthogonal functional readouts (morphology, mitochondrial function, calcium dynamics) establishing cell-autonomous role\",\n      \"pmids\": [\"36960552\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ADCK3 is a direct transcriptional target of tumor suppressor p53 in endometrial carcinoma cells; loss of ADCK3 suppresses MPA-mediated ferroptosis by abrogating ALOX15 transcriptional activation, placing ADCK3 downstream of p53 and upstream of ALOX15 in a ferroptosis pathway.\",\n      \"method\": \"Genome-wide CRISPR screen, ChIP-qPCR, luciferase reporter assay, western blotting, RT-qPCR\",\n      \"journal\": \"British journal of cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — CRISPR screen plus ChIP-qPCR and reporter assay establishing p53-ADCK3-ALOX15 axis; single lab, cancer-specific context\",\n      \"pmids\": [\"37402867\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"The COQ8A E548K (equivalent to human E551K) knock-in mutation in mice leads to variable instability of the COQ8A E548K protein and reduced expression of COQ5 and COQ7 in cerebellum and muscle (similar to constitutive knockout), demonstrating that COQ8A is required for maintaining protein levels of other CoQ biosynthesis pathway components; however, mitochondrial function and tissue architecture remained intact in the knock-in model.\",\n      \"method\": \"Knock-in mouse model, western blotting of CoQ pathway proteins, mitochondrial function assays, behavioral testing\",\n      \"journal\": \"bioRxiv\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo knock-in model with biochemical validation of pathway protein levels; preprint, not peer-reviewed\",\n      \"pmids\": [\"bio_10.1101_2025.04.23.650169\"],\n      \"is_preprint\": true\n    }\n  ],\n  \"current_model\": \"COQ8A (ADCK3) is a mitochondrial atypical kinase-like protein that localizes to mitochondrial cristae via an N-terminal signal and adopts a unique UbiB-family fold with ADP (rather than ATP) selectivity; it is required for coenzyme Q10 (CoQ10) biosynthesis by phosphorylating CoQ biosynthetic complex components (Coq3, Coq5, Coq7) and maintaining the protein stability of other CoQ pathway enzymes (COQ5, COQ7), with its enzymatic activity allosterically stimulated by CoQ precursor lipids; in Purkinje neurons, COQ8A loss causes mitochondrial dysfunction (primarily Complex IV), calcium dysregulation, and dendritic morphological defects that underlie cerebellar ataxia, and in cancer cells COQ8A acts as a p53 transcriptional target that promotes ferroptosis via ALOX15.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"COQ8A (ADCK3) is a mitochondrial UbiB-family atypical kinase-like protein required for coenzyme Q (CoQ10) biosynthesis, functioning as a regulatory hub for the CoQ biosynthetic machinery [#0, #2]. It localizes to mitochondrial cristae via an N-terminal signal, where it associates with the CoQ10 biosynthetic complex components Coq3, Coq5, Coq7, and Coq9, and its deficiency reduces cellular CoQ10 content [#6]. COQ8A promotes phosphorylation of Coq3, Coq5, and Coq7 in a Coq8-dependent manner and maintains the protein stability of CoQ pathway enzymes including COQ5 and COQ7 [#2, #10]. Structurally, it adopts an atypical protein kinase-like fold whose UbiB-specific features—an N-terminal domain occupying the substrate pocket and an A-rich loop—confer unusual selectivity for ADP over ATP that is essential for CoQ production in vivo, while the kinase domain exhibits Mg2+-dependent ATPase activity [#3, #5]. Its enzymatic activity is allosterically stimulated by CoQ precursor lipids: a precursor mimetic binds a conserved domain to increase nucleotide affinity and ATPase activity, establishing feedback regulation by pathway intermediates [#7]. In Purkinje neurons, cell-autonomous loss of COQ8A causes mitochondrial dysfunction (primarily Complex IV), intracellular calcium dysregulation, and abnormal dendritic arborization that underlie cerebellar ataxia [#8]. Separately, in endometrial carcinoma cells COQ8A acts as a direct p53 transcriptional target that promotes ferroptosis through transcriptional activation of ALOX15 [#9].\",\n  \"teleology\": [\n    {\n      \"year\": 2008,\n      \"claim\": \"Established that the human gene is a functional ortholog of yeast COQ8/bacterial UbiB required for CoQ biosynthesis, mapping disease-relevant missense changes onto a defined biosynthetic role.\",\n      \"evidence\": \"Yeast complementation and ubiquinone synthesis measurement with mutations introduced at conserved positions\",\n      \"pmids\": [\"18319074\", \"18319072\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not define the direct biochemical activity of the human protein\",\n        \"Did not identify physical substrates or partners\",\n        \"Phylogenetic classification as an atypical kinase was inference only\"\n      ]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Resolved whether ADCK3 acts directly on the CoQ machinery by showing Coq3, Coq5, and Coq7 are phosphorylated in a Coq8-dependent manner, framing it as a protein kinase for the biosynthetic complex.\",\n      \"evidence\": \"Yeast complementation with human ADCK3 plus two-dimensional gel phosphorylation analysis of Coq substrates\",\n      \"pmids\": [\"21296186\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Did not show ADCK3 directly phosphorylates these substrates in vitro\",\n        \"Did not exclude an indirect/scaffolding contribution to phosphorylation\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Explained the paradox of CoQ-essential but canonical-kinase-dead behavior by solving the structure and demonstrating UbiB-specific features that enforce ADP-over-ATP selectivity required for CoQ production.\",\n      \"evidence\": \"X-ray crystallography with A-rich loop mutagenesis and in vivo CoQ biosynthesis assays; companion biochemical ATPase assay of the recombinant kinase domain\",\n      \"pmids\": [\"25498144\", \"25540914\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Physiological phosphoacceptor and catalytic output remained undefined\",\n        \"ATPase activity demonstrated without mutagenesis validation in the in vitro study\"\n      ]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified a structural basis for higher-order assembly by showing the transmembrane helix homodimerizes via a Gly-zipper motif, implicating oligomerization in activity regulation.\",\n      \"evidence\": \"Computational transmembrane helix modeling validated by an experimental oligomerization assay\",\n      \"pmids\": [\"25216398\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of dimerization not directly demonstrated\",\n        \"Oligomeric state of full-length protein in mitochondria not established\"\n      ]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Localized the protein to mitochondrial cristae and tied its physical association with multiple CoQ biosynthetic components to a functional CoQ10 deficiency.\",\n      \"evidence\": \"Subcellular fractionation/immunofluorescence, CoQ10 quantification, and in vitro pulldown with recombinant Coq3/Coq5/Coq7/Coq9\",\n      \"pmids\": [\"26866375\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Interactions shown in vitro with recombinant proteins, not endogenous complex stoichiometry\",\n        \"Single lab without reciprocal validation\"\n      ]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined how the pathway feeds back on the enzyme by mapping a CoQ-precursor-mimetic binding site that allosterically raises nucleotide affinity and ATPase activity.\",\n      \"evidence\": \"NMR and hydrogen-deuterium exchange mass spectrometry with ATPase activity assay using 2-propylphenol\",\n      \"pmids\": [\"35904798\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Endogenous lipid ligand and physiological concentration range not established\",\n        \"Link between allosteric activation and substrate phosphorylation not shown\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Established cell-autonomous causation of cerebellar ataxia by showing Purkinje-neuron-specific loss drives the disease through mitochondrial (Complex IV) dysfunction, calcium dysregulation, and dendritic defects.\",\n      \"evidence\": \"Purkinje-specific conditional knockout mouse with behavioral, morphological, mitochondrial, and calcium-imaging readouts\",\n      \"pmids\": [\"36960552\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Mechanistic chain from CoQ loss to Complex IV and calcium phenotypes not fully resolved\",\n        \"Whether dendritic defects are primary or secondary to bioenergetic failure unresolved\"\n      ]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed COQ8A in a tumor-suppressor signaling axis, identifying it as a direct p53 target that promotes ferroptosis via ALOX15 in endometrial carcinoma.\",\n      \"evidence\": \"Genome-wide CRISPR screen, ChIP-qPCR, luciferase reporter, RT-qPCR and western blotting\",\n      \"pmids\": [\"37402867\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Mechanistic link between COQ8A's mitochondrial CoQ role and ALOX15 transcription not defined\",\n        \"Single lab in a cancer-specific context\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Tested a patient-equivalent point mutant in vivo, showing E548K destabilizes COQ8A and lowers COQ5/COQ7 levels, confirming a chaperone-like stabilization role distinct from overt mitochondrial failure.\",\n      \"evidence\": \"Knock-in mouse with western blotting of CoQ pathway proteins, mitochondrial assays, and behavioral testing (preprint)\",\n      \"pmids\": [\"bio_10.1101_2025.04.23.650169\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Preprint, not peer-reviewed\",\n        \"Why mitochondrial function and tissue architecture remained intact despite reduced pathway proteins is unexplained\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The direct in vitro phosphorylation reaction—whether COQ8A itself catalyzes phosphoryl transfer to a defined acceptor or acts primarily as an ADP-selective stabilizing scaffold—remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No reconstituted kinase reaction with an identified physiological substrate\",\n        \"Mechanistic unification of phosphorylation, protein stabilization, and ATPase activities is lacking\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [5, 7]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [3, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 2, 6]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"COQ3\", \"COQ5\", \"COQ7\", \"COQ9\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}