{"gene":"ALDH16A1","run_date":"2026-06-09T22:02:43","timeline":{"discoveries":[{"year":2009,"finding":"ALDH16A1 physically interacts with the SPG21 protein maspardin (ACP33); this interaction was identified by immunoprecipitation of maspardin followed by mass spectrometry identification of coprecipitating proteins, confirmed by overexpressed-protein co-immunoprecipitation and fusion-protein pull-down, and the two proteins colocalize in cells.","method":"Co-immunoprecipitation + mass spectrometry, pull-down assay, colocalization by immunofluorescence","journal":"Neurogenetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with MS identification plus orthogonal pull-down confirmation, single lab","pmids":["19184135"],"is_preprint":false},{"year":2013,"finding":"Human ALDH16A1 is predicted to lack aldehyde dehydrogenase catalytic activity because the essential catalytic cysteine (Cys-302 in bacterial/frog orthologs) is absent from mammalian and fish sequences. Molecular modeling further predicts that ALDH16A1 can interact with HPRT1 (hypoxanthine-guanine phosphoribosyltransferase) and that the gout-associated missense variant ALDH16A1*2 impairs this predicted interaction.","method":"Bioinformatic sequence analysis, molecular modeling/docking","journal":"Chemico-biological interactions","confidence":"Low","confidence_rationale":"Tier 4 / Weak — computational prediction only, no in vitro or cellular experimental confirmation of the HPRT1 interaction","pmids":["23348497"],"is_preprint":false},{"year":2017,"finding":"In Aldh16a1 knockout mice, ALDH16A1 protein is localized to proximal and distal convoluted tubule cells of the kidney cortex and to zone-3 hepatocytes. Loss of ALDH16A1 dysregulates expression of urate transporters (up-regulation of Abcc4 and Slc16a9; down-regulation of Slc17a3) and alters plasma lipid profiles, implicating ALDH16A1 in renal uric acid homeostasis.","method":"Gene-targeted Aldh16a1 knockout mouse, RNA-seq, gene ontology enrichment, plasma metabolomics, immunohistochemistry for localization","journal":"Chemico-biological interactions","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — clean KO model with defined molecular phenotype (transporter dysregulation) and metabolomics, single lab, two orthogonal methods","pmids":["28254523"],"is_preprint":false},{"year":2018,"finding":"Crystal structures of bacterial (Loktanella sp.) ALDH16 confirmed it is a bona fide enzyme with NAD+-binding, aldehyde oxidation, and esterase activities. In contrast, recombinant human ALDH16A1 lacks measurable aldehyde oxidation activity, consistent with absence of the catalytic Cys, establishing it as a pseudoenzyme. ALDH16 forms a unique dimer whose architecture mimics the classic ALDH superfamily dimer-of-dimer tetramer; small-angle X-ray scattering showed human ALDH16A1 shares the same dimer and overall fold.","method":"Recombinant protein expression, crystal structure determination (high-resolution), in vitro enzyme activity assays, SAXS","journal":"Journal of molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structures of bacterial ortholog plus SAXS of human ALDH16A1, in vitro biochemical activity assays, multiple orthogonal methods in one rigorous study","pmids":["30529746"],"is_preprint":false},{"year":2019,"finding":"Recombinant Xenopus tropicalis ALDH16B1 (the frog homolog of human ALDH16A1, predicted to be catalytically active due to retention of the catalytic Cys) was expressed in Sf9 cells, purified, and crystallized, yielding diffraction data to 2.5 Å; structure determination was in progress at time of publication.","method":"Recombinant protein expression (Sf9/baculovirus), affinity and size-exclusion chromatography purification, X-ray crystallography data collection","journal":"Chemico-biological interactions","confidence":"Low","confidence_rationale":"Tier 1 / Weak — crystallographic data collected but structure not yet solved at time of publication; finding is preliminary","pmids":["30894314"],"is_preprint":false},{"year":2025,"finding":"ALDH16A1 binds directly to thioredoxin (TXN) and facilitates its translocation to the lysosome for degradation; simultaneously, ALDH16A1 directly inhibits TXN's oxidoreductase function by occluding its active site. SMARCA4 promotes chromatin accessibility at the ALDH16A1 locus to drive its expression, and the resulting ALDH16A1-mediated suppression of TXN sensitizes NSCLC cells to ferroptosis.","method":"Co-immunoprecipitation, lysosomal fractionation, ferroptosis cell-death assays, SMARCA4 loss-of-function experiments, chromatin accessibility (ATAC-seq), TXN oxidoreductase activity assay","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, functional TXN activity assay, lysosomal trafficking assay, genetic epistasis (SMARCA4→ALDH16A1→TXN→ferroptosis), multiple orthogonal methods in one study","pmids":["40897711"],"is_preprint":false}],"current_model":"ALDH16A1 is an enzymatically inactive pseudoenzyme (lacking the catalytic cysteine) that functions through protein-protein interactions: it binds and inhibits thioredoxin (TXN) while facilitating its lysosomal degradation to promote ferroptosis downstream of SMARCA4; it also interacts with maspardin/ACP33 at trans-Golgi/late endosomal compartments; it is expressed in renal tubular cells and hepatocytes where it regulates uric acid transporter expression and is associated with gout risk, possibly via predicted (but not yet experimentally confirmed in vitro) interactions with HPRT1."},"narrative":{"mechanistic_narrative":"ALDH16A1 is a catalytically inactive member of the aldehyde dehydrogenase superfamily that operates as a pseudoenzyme scaffold, exerting its biological effects through protein-protein interactions rather than enzymatic catalysis [PMID:30529746, PMID:40897711]. Although the bacterial ortholog ALDH16 is a bona fide NAD+-dependent enzyme, human ALDH16A1 lacks the essential catalytic cysteine and shows no measurable aldehyde oxidation activity while retaining the conserved ALDH dimer fold [PMID:30529746]. Functionally, ALDH16A1 binds directly to thioredoxin (TXN), occluding its active site to inhibit its oxidoreductase activity and facilitating TXN translocation to the lysosome for degradation; this axis lies downstream of SMARCA4, which opens chromatin at the ALDH16A1 locus to drive its expression and thereby sensitizes non-small-cell lung cancer cells to ferroptosis [PMID:40897711]. ALDH16A1 also physically interacts with the SPG21 protein maspardin/ACP33 and colocalizes with it in cells [PMID:19184135], and in mouse it localizes to renal proximal and distal tubule cells and zone-3 hepatocytes, where its loss dysregulates urate transporter expression and plasma lipid profiles, implicating it in uric acid homeostasis [PMID:28254523].","teleology":[{"year":2009,"claim":"Before any function was assigned, the first direct binding partner of ALDH16A1 was identified, establishing it as an interaction partner of the spastic paraplegia protein maspardin.","evidence":"Co-immunoprecipitation with mass spectrometry, orthogonal pull-down, and immunofluorescence colocalization","pmids":["19184135"],"confidence":"Medium","gaps":["Functional consequence of the maspardin interaction not defined","Interaction interface and stoichiometry unmapped","Work from a single lab without independent replication"]},{"year":2013,"claim":"Sequence analysis raised the possibility that human ALDH16A1 is enzymatically dead and computationally linked it to purine metabolism, framing it as a non-catalytic interactor relevant to gout.","evidence":"Bioinformatic sequence analysis and molecular modeling/docking of the HPRT1 interaction and the gout-associated ALDH16A1*2 variant","pmids":["23348497"],"confidence":"Low","gaps":["HPRT1 interaction is computational only, with no in vitro or cellular confirmation","Catalytic inactivity inferred from sequence, not yet demonstrated biochemically","Functional effect of the ALDH16A1*2 variant not tested experimentally"]},{"year":2017,"claim":"A knockout mouse converted in silico inference into in vivo physiology, defining where ALDH16A1 is expressed and tying it to renal urate handling.","evidence":"Aldh16a1 knockout mouse with RNA-seq, plasma metabolomics, and immunohistochemistry showing urate transporter dysregulation and altered lipid profiles","pmids":["28254523"],"confidence":"Medium","gaps":["Molecular mechanism linking ALDH16A1 to transporter expression unknown","No demonstrated direct interaction with urate transporters or purine enzymes","Single-lab phenotype not replicated"]},{"year":2018,"claim":"Structural and biochemical work established definitively that human ALDH16A1 is a pseudoenzyme by comparing it to a catalytically competent bacterial ortholog.","evidence":"Crystal structures of bacterial ALDH16 with enzyme assays, plus SAXS and in vitro activity assays on recombinant human ALDH16A1","pmids":["30529746"],"confidence":"High","gaps":["High-resolution atomic structure of human ALDH16A1 not solved","Non-catalytic functional surfaces for partner binding not mapped","Physiological consequence of pseudoenzyme status not addressed in this study"]},{"year":2019,"claim":"Crystallographic effort on the catalytically active frog homolog was undertaken to provide a structural counterpoint to the inactive human protein.","evidence":"Recombinant Xenopus tropicalis ALDH16B1 expressed, purified, and crystallized with diffraction data to 2.5 Å","pmids":["30894314"],"confidence":"Low","gaps":["Structure not solved at time of publication; finding is preliminary","No comparison of active-site architecture to human ALDH16A1 yet available"]},{"year":2025,"claim":"A defined molecular function was finally established: ALDH16A1 acts as a TXN-inhibiting, TXN-degrading scaffold within a SMARCA4-driven ferroptosis pathway in cancer.","evidence":"Reciprocal Co-IP, TXN oxidoreductase activity assay, lysosomal fractionation, ATAC-seq, and SMARCA4 loss-of-function with ferroptosis assays in NSCLC cells","pmids":["40897711"],"confidence":"High","gaps":["Structural basis of TXN active-site occlusion not resolved","Mechanism of ALDH16A1-mediated lysosomal targeting of TXN undefined","Relationship between the TXN/ferroptosis role and the renal/urate role unexplored"]},{"year":null,"claim":"How the distinct ALDH16A1 activities — maspardin binding, renal urate regulation, and TXN-mediated ferroptosis control — are integrated into a single mechanistic framework remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unifying model connecting the trans-Golgi/endosomal maspardin interaction to the lysosomal TXN-degradation function","Predicted HPRT1 interaction still lacks experimental confirmation","No high-resolution structure of human ALDH16A1 bound to any partner"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5]}],"localization":[{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[5]}],"complexes":[],"partners":["TXN","SPG21","SMARCA4"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8IZ83","full_name":"Aldehyde dehydrogenase family 16 member A1","aliases":[],"length_aa":802,"mass_kda":85.1,"function":"","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q8IZ83/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/ALDH16A1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000161618","cell_line_id":"CID000980","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"vesicles","grade":3}],"interactors":[{"gene":"DERA","stoichiometry":10.0},{"gene":"TRIAP1","stoichiometry":0.2},{"gene":"KIAA0430","stoichiometry":0.2},{"gene":"DCTN2","stoichiometry":0.2},{"gene":"PRR14L","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000980","total_profiled":1310},"omim":[{"mim_id":"614747","title":"URIC ACID CONCENTRATION, SERUM, QUANTITATIVE TRAIT LOCUS 6; UAQTL6","url":"https://www.omim.org/entry/614747"},{"mim_id":"614746","title":"URIC ACID CONCENTRATION, SERUM, QUANTITATIVE TRAIT LOCUS 5; UAQTL5","url":"https://www.omim.org/entry/614746"},{"mim_id":"613358","title":"ALDEHYDE DEHYDROGENASE 16 FAMILY, MEMBER A1; ALDH16A1","url":"https://www.omim.org/entry/613358"},{"mim_id":"608181","title":"ACIDIC CLUSTER PROTEIN, 33-KD; ACP33","url":"https://www.omim.org/entry/608181"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/ALDH16A1"},"hgnc":{"alias_symbol":["MGC10204"],"prev_symbol":[]},"alphafold":{"accession":"Q8IZ83","domains":[{"cath_id":"3.40.605.10","chopping":"27-274_484-488","consensus_level":"high","plddt":94.2785,"start":27,"end":488},{"cath_id":"3.40.309.10","chopping":"278-458","consensus_level":"high","plddt":92.7153,"start":278,"end":458},{"cath_id":"3.40.605.10","chopping":"531-790","consensus_level":"high","plddt":92.9315,"start":531,"end":790}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IZ83","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IZ83-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IZ83-F1-predicted_aligned_error_v6.png","plddt_mean":91.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=ALDH16A1","jax_strain_url":"https://www.jax.org/strain/search?query=ALDH16A1"},"sequence":{"accession":"Q8IZ83","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IZ83.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IZ83/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IZ83"}},"corpus_meta":[{"pmid":"21983786","id":"PMC_21983786","title":"Identification of low-frequency variants associated with gout and serum uric acid levels.","date":"2011","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/21983786","citation_count":118,"is_preprint":false},{"pmid":"19184135","id":"PMC_19184135","title":"Interaction of the SPG21 protein ACP33/maspardin with the aldehyde dehydrogenase ALDH16A1.","date":"2009","source":"Neurogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/19184135","citation_count":36,"is_preprint":false},{"pmid":"23348497","id":"PMC_23348497","title":"ALDH16A1 is a novel non-catalytic enzyme that may be involved in the etiology of gout via protein-protein interactions with HPRT1.","date":"2013","source":"Chemico-biological interactions","url":"https://pubmed.ncbi.nlm.nih.gov/23348497","citation_count":32,"is_preprint":false},{"pmid":"20927131","id":"PMC_20927131","title":"A DEAB-sensitive aldehyde dehydrogenase regulates hematopoietic stem and progenitor cells development during primitive hematopoiesis in zebrafish embryos.","date":"2010","source":"Leukemia","url":"https://pubmed.ncbi.nlm.nih.gov/20927131","citation_count":22,"is_preprint":false},{"pmid":"35116021","id":"PMC_35116021","title":"The ALDH Family Contributes to Immunocyte Infiltration, Proliferation and Epithelial-Mesenchymal Transformation in Glioma.","date":"2022","source":"Frontiers in immunology","url":"https://pubmed.ncbi.nlm.nih.gov/35116021","citation_count":21,"is_preprint":false},{"pmid":"28254523","id":"PMC_28254523","title":"Transcriptomic analysis and plasma metabolomics in Aldh16a1-null mice reveals a potential role of ALDH16A1 in renal function.","date":"2017","source":"Chemico-biological interactions","url":"https://pubmed.ncbi.nlm.nih.gov/28254523","citation_count":18,"is_preprint":false},{"pmid":"30529746","id":"PMC_30529746","title":"Crystal Structure of Aldehyde Dehydrogenase 16 Reveals Trans-Hierarchical Structural Similarity and a New Dimer.","date":"2018","source":"Journal of molecular biology","url":"https://pubmed.ncbi.nlm.nih.gov/30529746","citation_count":17,"is_preprint":false},{"pmid":"34732286","id":"PMC_34732286","title":"The genetic basis of urate control and gout: Insights into molecular pathogenesis from follow-up study of genome-wide association study loci.","date":"2021","source":"Best practice & research. Clinical rheumatology","url":"https://pubmed.ncbi.nlm.nih.gov/34732286","citation_count":15,"is_preprint":false},{"pmid":"40897711","id":"PMC_40897711","title":"Targeting ALDH16A1 mediated thioredoxin lysosomal degradation to enhance ferroptosis susceptibility in SMARCA4-deficient NSCLC.","date":"2025","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/40897711","citation_count":6,"is_preprint":false},{"pmid":"30894314","id":"PMC_30894314","title":"Expression, purification and crystallization of the novel Xenopus tropicalis ALDH16B1, a homologue of human ALDH16A1.","date":"2019","source":"Chemico-biological interactions","url":"https://pubmed.ncbi.nlm.nih.gov/30894314","citation_count":3,"is_preprint":false},{"pmid":"38644525","id":"PMC_38644525","title":"Single-nucleus transcriptomics and chromatin accessibility analysis of musk gland development in Chinese forest musk deer (Moschus berezovskii).","date":"2024","source":"Integrative zoology","url":"https://pubmed.ncbi.nlm.nih.gov/38644525","citation_count":3,"is_preprint":false},{"pmid":"40898360","id":"PMC_40898360","title":"Identification and validation of a tear fluid-derived protein biomarker signature in patients with amyotrophic lateral sclerosis.","date":"2025","source":"Acta neuropathologica communications","url":"https://pubmed.ncbi.nlm.nih.gov/40898360","citation_count":2,"is_preprint":false},{"pmid":"41328062","id":"PMC_41328062","title":"Syndrome Differentiation and Treatment of Psoriasis by Traditional Chinese Medicines: An Integrating Study of Multi-Omics Analysis and Experimental Validation.","date":"2025","source":"Journal of inflammation research","url":"https://pubmed.ncbi.nlm.nih.gov/41328062","citation_count":1,"is_preprint":false},{"pmid":"40537683","id":"PMC_40537683","title":"Druggable Targets for Postpartum Depression: A Mendelian Randomization and Colocalization Study.","date":"2025","source":"Cellular and molecular neurobiology","url":"https://pubmed.ncbi.nlm.nih.gov/40537683","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":9134,"output_tokens":1771,"usd":0.026984,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8625,"output_tokens":2478,"usd":0.052538,"stage2_stop_reason":"end_turn"},"total_usd":0.079522,"stage1_batch_id":"msgbatch_0179Z2pxRYBsXi2xADneafRw","stage2_batch_id":"msgbatch_01LaY9ZaVdgjWArcZo9eqQE5","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2009,\n      \"finding\": \"ALDH16A1 physically interacts with the SPG21 protein maspardin (ACP33); this interaction was identified by immunoprecipitation of maspardin followed by mass spectrometry identification of coprecipitating proteins, confirmed by overexpressed-protein co-immunoprecipitation and fusion-protein pull-down, and the two proteins colocalize in cells.\",\n      \"method\": \"Co-immunoprecipitation + mass spectrometry, pull-down assay, colocalization by immunofluorescence\",\n      \"journal\": \"Neurogenetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with MS identification plus orthogonal pull-down confirmation, single lab\",\n      \"pmids\": [\"19184135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Human ALDH16A1 is predicted to lack aldehyde dehydrogenase catalytic activity because the essential catalytic cysteine (Cys-302 in bacterial/frog orthologs) is absent from mammalian and fish sequences. Molecular modeling further predicts that ALDH16A1 can interact with HPRT1 (hypoxanthine-guanine phosphoribosyltransferase) and that the gout-associated missense variant ALDH16A1*2 impairs this predicted interaction.\",\n      \"method\": \"Bioinformatic sequence analysis, molecular modeling/docking\",\n      \"journal\": \"Chemico-biological interactions\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 4 / Weak — computational prediction only, no in vitro or cellular experimental confirmation of the HPRT1 interaction\",\n      \"pmids\": [\"23348497\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"In Aldh16a1 knockout mice, ALDH16A1 protein is localized to proximal and distal convoluted tubule cells of the kidney cortex and to zone-3 hepatocytes. Loss of ALDH16A1 dysregulates expression of urate transporters (up-regulation of Abcc4 and Slc16a9; down-regulation of Slc17a3) and alters plasma lipid profiles, implicating ALDH16A1 in renal uric acid homeostasis.\",\n      \"method\": \"Gene-targeted Aldh16a1 knockout mouse, RNA-seq, gene ontology enrichment, plasma metabolomics, immunohistochemistry for localization\",\n      \"journal\": \"Chemico-biological interactions\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KO model with defined molecular phenotype (transporter dysregulation) and metabolomics, single lab, two orthogonal methods\",\n      \"pmids\": [\"28254523\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Crystal structures of bacterial (Loktanella sp.) ALDH16 confirmed it is a bona fide enzyme with NAD+-binding, aldehyde oxidation, and esterase activities. In contrast, recombinant human ALDH16A1 lacks measurable aldehyde oxidation activity, consistent with absence of the catalytic Cys, establishing it as a pseudoenzyme. ALDH16 forms a unique dimer whose architecture mimics the classic ALDH superfamily dimer-of-dimer tetramer; small-angle X-ray scattering showed human ALDH16A1 shares the same dimer and overall fold.\",\n      \"method\": \"Recombinant protein expression, crystal structure determination (high-resolution), in vitro enzyme activity assays, SAXS\",\n      \"journal\": \"Journal of molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structures of bacterial ortholog plus SAXS of human ALDH16A1, in vitro biochemical activity assays, multiple orthogonal methods in one rigorous study\",\n      \"pmids\": [\"30529746\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Recombinant Xenopus tropicalis ALDH16B1 (the frog homolog of human ALDH16A1, predicted to be catalytically active due to retention of the catalytic Cys) was expressed in Sf9 cells, purified, and crystallized, yielding diffraction data to 2.5 Å; structure determination was in progress at time of publication.\",\n      \"method\": \"Recombinant protein expression (Sf9/baculovirus), affinity and size-exclusion chromatography purification, X-ray crystallography data collection\",\n      \"journal\": \"Chemico-biological interactions\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 1 / Weak — crystallographic data collected but structure not yet solved at time of publication; finding is preliminary\",\n      \"pmids\": [\"30894314\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"ALDH16A1 binds directly to thioredoxin (TXN) and facilitates its translocation to the lysosome for degradation; simultaneously, ALDH16A1 directly inhibits TXN's oxidoreductase function by occluding its active site. SMARCA4 promotes chromatin accessibility at the ALDH16A1 locus to drive its expression, and the resulting ALDH16A1-mediated suppression of TXN sensitizes NSCLC cells to ferroptosis.\",\n      \"method\": \"Co-immunoprecipitation, lysosomal fractionation, ferroptosis cell-death assays, SMARCA4 loss-of-function experiments, chromatin accessibility (ATAC-seq), TXN oxidoreductase activity assay\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, functional TXN activity assay, lysosomal trafficking assay, genetic epistasis (SMARCA4→ALDH16A1→TXN→ferroptosis), multiple orthogonal methods in one study\",\n      \"pmids\": [\"40897711\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"ALDH16A1 is an enzymatically inactive pseudoenzyme (lacking the catalytic cysteine) that functions through protein-protein interactions: it binds and inhibits thioredoxin (TXN) while facilitating its lysosomal degradation to promote ferroptosis downstream of SMARCA4; it also interacts with maspardin/ACP33 at trans-Golgi/late endosomal compartments; it is expressed in renal tubular cells and hepatocytes where it regulates uric acid transporter expression and is associated with gout risk, possibly via predicted (but not yet experimentally confirmed in vitro) interactions with HPRT1.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"ALDH16A1 is a catalytically inactive member of the aldehyde dehydrogenase superfamily that operates as a pseudoenzyme scaffold, exerting its biological effects through protein-protein interactions rather than enzymatic catalysis [#3, #5]. Although the bacterial ortholog ALDH16 is a bona fide NAD+-dependent enzyme, human ALDH16A1 lacks the essential catalytic cysteine and shows no measurable aldehyde oxidation activity while retaining the conserved ALDH dimer fold [#3]. Functionally, ALDH16A1 binds directly to thioredoxin (TXN), occluding its active site to inhibit its oxidoreductase activity and facilitating TXN translocation to the lysosome for degradation; this axis lies downstream of SMARCA4, which opens chromatin at the ALDH16A1 locus to drive its expression and thereby sensitizes non-small-cell lung cancer cells to ferroptosis [#5]. ALDH16A1 also physically interacts with the SPG21 protein maspardin/ACP33 and colocalizes with it in cells [#0], and in mouse it localizes to renal proximal and distal tubule cells and zone-3 hepatocytes, where its loss dysregulates urate transporter expression and plasma lipid profiles, implicating it in uric acid homeostasis [#2].\",\n  \"teleology\": [\n    {\n      \"year\": 2009,\n      \"claim\": \"Before any function was assigned, the first direct binding partner of ALDH16A1 was identified, establishing it as an interaction partner of the spastic paraplegia protein maspardin.\",\n      \"evidence\": \"Co-immunoprecipitation with mass spectrometry, orthogonal pull-down, and immunofluorescence colocalization\",\n      \"pmids\": [\"19184135\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Functional consequence of the maspardin interaction not defined\",\n        \"Interaction interface and stoichiometry unmapped\",\n        \"Work from a single lab without independent replication\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Sequence analysis raised the possibility that human ALDH16A1 is enzymatically dead and computationally linked it to purine metabolism, framing it as a non-catalytic interactor relevant to gout.\",\n      \"evidence\": \"Bioinformatic sequence analysis and molecular modeling/docking of the HPRT1 interaction and the gout-associated ALDH16A1*2 variant\",\n      \"pmids\": [\"23348497\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"HPRT1 interaction is computational only, with no in vitro or cellular confirmation\",\n        \"Catalytic inactivity inferred from sequence, not yet demonstrated biochemically\",\n        \"Functional effect of the ALDH16A1*2 variant not tested experimentally\"\n      ]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"A knockout mouse converted in silico inference into in vivo physiology, defining where ALDH16A1 is expressed and tying it to renal urate handling.\",\n      \"evidence\": \"Aldh16a1 knockout mouse with RNA-seq, plasma metabolomics, and immunohistochemistry showing urate transporter dysregulation and altered lipid profiles\",\n      \"pmids\": [\"28254523\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"Molecular mechanism linking ALDH16A1 to transporter expression unknown\",\n        \"No demonstrated direct interaction with urate transporters or purine enzymes\",\n        \"Single-lab phenotype not replicated\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Structural and biochemical work established definitively that human ALDH16A1 is a pseudoenzyme by comparing it to a catalytically competent bacterial ortholog.\",\n      \"evidence\": \"Crystal structures of bacterial ALDH16 with enzyme assays, plus SAXS and in vitro activity assays on recombinant human ALDH16A1\",\n      \"pmids\": [\"30529746\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"High-resolution atomic structure of human ALDH16A1 not solved\",\n        \"Non-catalytic functional surfaces for partner binding not mapped\",\n        \"Physiological consequence of pseudoenzyme status not addressed in this study\"\n      ]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Crystallographic effort on the catalytically active frog homolog was undertaken to provide a structural counterpoint to the inactive human protein.\",\n      \"evidence\": \"Recombinant Xenopus tropicalis ALDH16B1 expressed, purified, and crystallized with diffraction data to 2.5 Å\",\n      \"pmids\": [\"30894314\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"Structure not solved at time of publication; finding is preliminary\",\n        \"No comparison of active-site architecture to human ALDH16A1 yet available\"\n      ]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A defined molecular function was finally established: ALDH16A1 acts as a TXN-inhibiting, TXN-degrading scaffold within a SMARCA4-driven ferroptosis pathway in cancer.\",\n      \"evidence\": \"Reciprocal Co-IP, TXN oxidoreductase activity assay, lysosomal fractionation, ATAC-seq, and SMARCA4 loss-of-function with ferroptosis assays in NSCLC cells\",\n      \"pmids\": [\"40897711\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"Structural basis of TXN active-site occlusion not resolved\",\n        \"Mechanism of ALDH16A1-mediated lysosomal targeting of TXN undefined\",\n        \"Relationship between the TXN/ferroptosis role and the renal/urate role unexplored\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the distinct ALDH16A1 activities — maspardin binding, renal urate regulation, and TXN-mediated ferroptosis control — are integrated into a single mechanistic framework remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No unifying model connecting the trans-Golgi/endosomal maspardin interaction to the lysosomal TXN-degradation function\",\n        \"Predicted HPRT1 interaction still lacks experimental confirmation\",\n        \"No high-resolution structure of human ALDH16A1 bound to any partner\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"TXN\", \"SPG21\", \"SMARCA4\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"faith_supported":4,"faith_total":4,"faith_pct":100.0}}