{"gene":"TRIAP1","run_date":"2026-04-28T21:42:59","timeline":{"discoveries":[{"year":2013,"finding":"TRIAP1 forms a complex with PRELI in the mitochondrial intermembrane space (IMS) and the TRIAP1/PRELI complex exerts lipid transfer activity in vitro, supplying phosphatidic acid (PA) for cardiolipin (CL) synthesis in the inner membrane. Loss of TRIAP1 or PRELI impairs CL accumulation, facilitates cytochrome c release, and renders cells vulnerable to apoptosis.","method":"Co-immunoprecipitation, in vitro lipid transfer assay, siRNA knockdown, overexpression, cytochrome c release assay, apoptosis assay with exogenous phosphatidylglycerol rescue","journal":"Cell metabolism","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstituted lipid transfer activity plus genetic loss-of-function with defined mechanistic readouts; highly cited foundational study","pmids":["23931759"],"is_preprint":false},{"year":2005,"finding":"TRIAP1 (p53CSV) is a p53 target gene that modulates apoptotic pathways through interaction with Hsp70, which inhibits the activity of apoptosis protease activating factor-1 (Apaf-1). Overexpression protected cells from apoptosis after DNA damage, while siRNA-mediated knockdown enhanced apoptosis.","method":"siRNA knockdown, overexpression, co-immunoprecipitation with Hsp70, apoptosis assay, p53-binding site identification in gene","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP with Hsp70 and functional knockdown/overexpression assays, single lab","pmids":["15735003"],"is_preprint":false},{"year":2010,"finding":"The yeast TRIAP1 ortholog Mdm35 (a twin Cx9C protein) is a novel interaction partner of Ups1 and Ups2 (PRELI-like proteins) in the IMS. Binding to Mdm35 ensures import and protects Ups1/Ups2 against proteolysis by distinct mitochondrial peptidases (Yme1 for Ups2; Yme1 and Atp23 for Ups1), thereby regulating CL and PE accumulation in mitochondria.","method":"Co-immunoprecipitation, proteolysis assays, genetic deletion analysis, import assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (Co-IP, proteolysis, genetics) in foundational yeast ortholog study, highly cited","pmids":["20657548"],"is_preprint":false},{"year":2015,"finding":"Crystal structure of the yeast Ups1-Mdm35 (PRELI-TRIAP1 ortholog) complex with PA bound was solved. Ups1 features a barrel-like structure with a tunnel-like pocket accommodating PA; helix α2 acts as a lid. Mdm35 adopts a three-helical clamp structure wrapping around Ups1. Hydrophobic residues lining the pocket and helix α2 are critical for PA binding and transfer, demonstrated by mutagenesis.","method":"X-ray crystallography, in vitro PA-binding assay, lipid transfer assay, site-directed mutagenesis","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 1 — crystal structure combined with in vitro functional assays and mutagenesis","pmids":["26071601"],"is_preprint":false},{"year":2016,"finding":"The human SLMO2-TRIAP1 complex (Ups2-Mdm35 in yeast) functions as a phosphatidylserine (PS)-specific lipid transfer protein in the mitochondrial IMS, enabling PE synthesis by the inner membrane decarboxylase Psd1. MICOS deficiency combined with reduced Ups2-Mdm35 PS transfer preserves mitochondrial respiration and cristae formation.","method":"Genetic deletion, in vitro lipid transfer assay, mitochondrial fractionation, respiration measurements, electron microscopy","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstituted PS transfer activity plus genetic epistasis with MICOS, multiple orthogonal methods","pmids":["27241913"],"is_preprint":false},{"year":2016,"finding":"A recombinant Ups2-Mdm35 (SLMO2-TRIAP1 ortholog) fusion protein exhibited phospholipid (PS) transfer activity between liposomes in vitro. UPS2/MDM35 null mutations greatly attenuated PS-to-PE conversion in respiration-active yeast, and UPS2 expression was elevated during the diauxic shift.","method":"In vitro liposome-based lipid transfer assay, genetic deletion, isotope labeling/PS-to-PE conversion assay","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 1 — direct in vitro lipid transfer reconstitution plus in vivo genetic validation","pmids":["27354379"],"is_preprint":false},{"year":2013,"finding":"In a genome-wide genetic screen, TRIAP1 was identified as a specific repressor of p21 (CDKN1A) expression upon p53 activation; its depletion slows cell-cycle progression without strongly promoting apoptosis, placing TRIAP1 as a pathway-specific coregulator that biases p53 responses toward cell-cycle arrest outcomes.","method":"Genome-wide RNAi screen (p21:PUMA ratio readout), siRNA knockdown, flow cytometry cell-cycle analysis","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — genome-wide functional screen with defined readout, single lab","pmids":["23684607"],"is_preprint":false},{"year":2023,"finding":"Exercise training downregulates the mitochondrial disulfide relay carrier CHCHD4, which decreases import of TRIAP1 into mitochondria. Reduced mitochondrial TRIAP1 lowers cardiolipin levels and promotes VDAC oligomerization, facilitating mtDNA release that activates cGAS-STING/NF-κB innate immune signaling, downregulates MyoD, and drives formation of oxidative slow-twitch muscle fibers. CHCHD4 haploinsufficiency recapitulates this pathway in mice.","method":"CHCHD4 haploinsufficiency mouse model, mitochondrial import assays, cardiolipin measurement, VDAC oligomerization assay, cGAS-STING signaling readouts, muscle fiber-type analysis","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal in vivo and cell-based methods establishing pathway position with defined mechanistic readouts","pmids":["38157298"],"is_preprint":false},{"year":2025,"finding":"TRIAP1 is imported into the IMS via the MIA40 disulfide relay system. In its reduced cytosolic state, TRIAP1 rapidly populates a hydrophobic, alpha-helical molten globule intermediate that creates a non-native Cys37-Cys47 kinetic trap slowing oxidative folding. MIA40 accelerates TRIAP1 folding 30-fold by driving oxidation of the inner disulfide bond (Cys18-Cys37) and then the outer bond (Cys8-Cys47) to achieve the native two-disulfide-bridged structure, bypassing the kinetic trap.","method":"NMR, in vitro oxidative folding assays, mutagenesis of cysteines, MIA40 interaction assays, biophysical characterization of folding intermediates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — structural/biophysical characterization combined with in vitro reconstitution of MIA40-catalyzed folding and mutagenesis","pmids":["39909379"],"is_preprint":false},{"year":2016,"finding":"Stable knockdown of TRIAP1 in RPMI8226 multiple myeloma cells increased late apoptosis accompanied by upregulation of APAF1 and Caspase-9 expression and increased Caspase-9 and Caspase-3/7 activity, establishing that TRIAP1 functions to suppress the APAF1/Caspase-9 apoptosome pathway.","method":"Lentiviral shRNA stable knockdown, flow cytometry (annexin V/PI), caspase activity assays, qPCR","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 — clean stable KD with multiple orthogonal apoptosis readouts, single lab","pmids":["27032384"],"is_preprint":false},{"year":2023,"finding":"Triap1 upregulation in human cells surviving nocodazole-induced prolonged mitotic arrest leads to retention of cytochrome c in the mitochondria, opposing partial caspase activation caused by the drug. Increasing Triap1 levels reduced DNA damage and p21 activation, allowing cells to escape G1 arrest and resume proliferation; decreasing Triap1 re-sensitized cells to nocodazole.","method":"Long-term live-cell imaging, cytochrome c retention assay, caspase activity assay, overexpression and knockdown, flow cytometry for DNA damage and p21","journal":"Cell reports","confidence":"Medium","confidence_rationale":"Tier 2 — gain- and loss-of-function with mechanistic readout (cytochrome c retention, caspase activation), single lab","pmids":["36917609"],"is_preprint":false},{"year":2020,"finding":"TRIAP1 knockdown in NSCLC cells decreased the expression of antioxidant proteins (TMX1, TMX2, TXN, GLRX2, GLRX3, PRDX3, PRDX4, PRDX6) and impaired radiation-induced upregulation of these proteins, increasing intracellular ROS and sensitizing cells to ionizing radiation, identifying TRIAP1 as a regulator of redox homeostasis.","method":"siRNA knockdown, western blotting for antioxidant proteins, ROS measurement, clonogenic survival assay, apoptosis assay","journal":"Thoracic cancer","confidence":"Medium","confidence_rationale":"Tier 2-3 — knockdown with defined molecular readouts across multiple antioxidant proteins, single lab","pmids":["32096592"],"is_preprint":false},{"year":2025,"finding":"SLMO2 (PRELI) physically interacts with TRIAP1 in ovarian cancer cells; this interaction enhances mitochondrial membrane potential, reduces ROS, inhibits autophagy, and suppresses apoptosis, consistent with the SLMO2-TRIAP1 complex regulating mitochondrial function.","method":"Co-immunoprecipitation/interaction assay, flow cytometry (membrane potential, ROS), western blot for autophagy proteins, xenograft tumor model","journal":"Histology and histopathology","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP plus functional assays, single lab, newly published","pmids":["40654025"],"is_preprint":false},{"year":2022,"finding":"TRIAP1 depletion in colorectal cancer cells perturbs mitochondrial ultrastructure and causes extramitochondrial perturbations including changes in ER-dependent lipid homeostasis and induction of a p53-mediated stress response. Loss of TRIAP1 also confers p53-mediated resistance to glutamine deprivation, demonstrating extramitochondrial functions of TRIAP1.","method":"siRNA/shRNA knockdown, electron microscopy, lipidomics, metabolomics, p53 pathway reporter assays, glutamine deprivation survival assays","journal":"Frontiers in oncology","confidence":"Medium","confidence_rationale":"Tier 2-3 — multiple orthogonal methods revealing extramitochondrial consequences, single lab","pmids":["36387192"],"is_preprint":false}],"current_model":"TRIAP1 (p53CSV) is a p53-induced small IMS protein that forms a complex with PRELI/SLMO2 family members (imported via MIA40-catalyzed disulfide bond formation) to act as an intramitochondrial lipid transfer protein shuttling phosphatidic acid (and, as its homolog Ups2-Mdm35, phosphatidylserine) between mitochondrial membranes for cardiolipin and PE synthesis; loss of TRIAP1 reduces cardiolipin levels, promotes VDAC oligomerization and cytochrome c release, and triggers apoptosis via the APAF1/caspase-9 pathway, while cytosolic TRIAP1 additionally suppresses apoptosome formation through Hsp70 interaction, collectively placing TRIAP1 at the intersection of mitochondrial phospholipid homeostasis and p53-dependent cell survival."},"narrative":{"teleology":[{"year":2005,"claim":"Establishing that TRIAP1 is a p53-inducible anti-apoptotic factor answered how cells modulate death sensitivity after DNA damage, revealing that TRIAP1 interacts with Hsp70 to inhibit APAF1-dependent apoptosis.","evidence":"Co-immunoprecipitation with Hsp70, siRNA knockdown and overexpression in human cancer cells","pmids":["15735003"],"confidence":"Medium","gaps":["Hsp70 interaction was demonstrated by single Co-IP without reciprocal validation or domain mapping","cytosolic vs. mitochondrial pool contributions to anti-apoptotic effect not distinguished","mechanism by which TRIAP1-Hsp70 inhibits APAF1 not defined"]},{"year":2010,"claim":"Identification of the yeast ortholog Mdm35 as a binding partner of Ups1/Ups2 that protects them from IMS proteases established the conserved chaperoning function of TRIAP1-family proteins within mitochondria, resolving how PRELI-like proteins are stabilized after import.","evidence":"Co-immunoprecipitation, protease sensitivity assays, and genetic deletion in S. cerevisiae","pmids":["20657548"],"confidence":"High","gaps":["Whether human TRIAP1 similarly protects PRELI from degradation was not tested","identity of the relevant human IMS proteases unknown"]},{"year":2013,"claim":"Reconstitution of phosphatidic acid transfer activity by the TRIAP1–PRELI complex in vitro, coupled with demonstration that loss of either subunit impairs cardiolipin accumulation and sensitizes cells to cytochrome c release, defined the primary molecular function of TRIAP1 as a lipid transfer cofactor essential for cardiolipin biosynthesis.","evidence":"In vitro lipid transfer assay, siRNA knockdown, cytochrome c release assay, phosphatidylglycerol rescue in human cells","pmids":["23931759"],"confidence":"High","gaps":["Whether TRIAP1 contributes catalytically to transfer or solely stabilizes PRELI not resolved","structural basis of human complex not determined at this point"]},{"year":2013,"claim":"A genome-wide RNAi screen placed TRIAP1 as a pathway-specific modulator of p53 signaling by showing that its depletion selectively upregulates p21 while sparing PUMA, revealing an unexpected nuclear/cytoplasmic regulatory role beyond mitochondrial lipid transfer.","evidence":"Genome-wide RNAi screen with p21:PUMA ratio readout, flow cytometry in human cells","pmids":["23684607"],"confidence":"Medium","gaps":["Mechanism by which TRIAP1 selectively represses p21 not identified","whether this reflects a direct transcriptional role or indirect metabolic consequence unknown"]},{"year":2015,"claim":"Solving the crystal structure of the Ups1–Mdm35 complex with bound PA revealed how TRIAP1 wraps around its PRELI partner as a three-helical clamp while a hydrophobic tunnel and lid helix in Ups1 accommodate the lipid cargo, providing the structural basis for lipid specificity.","evidence":"X-ray crystallography, mutagenesis, in vitro PA-binding and transfer assays using yeast orthologs","pmids":["26071601"],"confidence":"High","gaps":["Human TRIAP1–PRELI structure not yet solved","how membrane association and lipid extraction/insertion occur structurally not resolved"]},{"year":2016,"claim":"Demonstration that the SLMO2–TRIAP1 (Ups2–Mdm35) complex transfers phosphatidylserine for PE synthesis expanded the functional repertoire of TRIAP1 beyond cardiolipin metabolism, establishing it as a shared cofactor for distinct lipid transfer specificities dictated by the PRELI-family partner.","evidence":"In vitro liposome-based PS transfer assay, genetic epistasis with MICOS, isotope labeling in yeast and human cells","pmids":["27241913","27354379"],"confidence":"High","gaps":["Regulation of partner choice (PRELI vs. SLMO2) not understood","whether additional PRELI-family partners exist for TRIAP1 not addressed"]},{"year":2016,"claim":"Stable TRIAP1 knockdown in myeloma cells confirmed that TRIAP1 suppresses the APAF1/caspase-9 intrinsic apoptosis pathway, linking its lipid transfer function to control of the mitochondrial apoptotic cascade.","evidence":"Lentiviral shRNA knockdown, caspase-9/3/7 activity assays, APAF1 qPCR in RPMI8226 cells","pmids":["27032384"],"confidence":"Medium","gaps":["Whether apoptosis sensitization is solely due to cardiolipin loss or also involves cytosolic TRIAP1 functions not distinguished","single cell line"]},{"year":2020,"claim":"TRIAP1 depletion reduced expression of multiple antioxidant proteins and elevated ROS, uncovering a role for TRIAP1 in redox homeostasis that explains its ability to protect cells against ionizing radiation.","evidence":"siRNA knockdown, western blotting for TMX1/2, TXN, GLRX2/3, PRDX3/4/6, ROS measurement, clonogenic survival in NSCLC cells","pmids":["32096592"],"confidence":"Medium","gaps":["Whether redox effects are a direct consequence of impaired cardiolipin/PE metabolism or an independent function is unclear","single cell type, no rescue experiment reported"]},{"year":2022,"claim":"Lipidomic and metabolomic profiling of TRIAP1-depleted cells revealed extramitochondrial consequences including altered ER lipid homeostasis and p53-dependent stress responses, broadening the impact of TRIAP1 loss beyond mitochondria.","evidence":"siRNA/shRNA knockdown, electron microscopy, lipidomics, metabolomics, glutamine deprivation assays in colorectal cancer cells","pmids":["36387192"],"confidence":"Medium","gaps":["Causal chain from mitochondrial lipid deficiency to ER perturbation not established","whether extramitochondrial effects reflect a direct ER pool of TRIAP1 unknown"]},{"year":2023,"claim":"Placing TRIAP1 downstream of CHCHD4/MIA40-dependent import in exercised muscle showed that reduced TRIAP1 import lowers cardiolipin, promotes VDAC oligomerization and mtDNA release, and activates cGAS-STING signaling to drive slow-twitch fiber formation, establishing an in vivo physiological consequence of TRIAP1 regulation.","evidence":"CHCHD4 haploinsufficient mice, mitochondrial import assays, cardiolipin measurement, VDAC oligomerization assay, cGAS-STING readouts, muscle fiber-type analysis","pmids":["38157298"],"confidence":"High","gaps":["Whether TRIAP1 is the sole CHCHD4 substrate responsible for the phenotype not proven","applicability beyond skeletal muscle not tested"]},{"year":2023,"claim":"TRIAP1 upregulation during prolonged mitotic arrest was shown to retain cytochrome c in mitochondria and suppress partial caspase activation, enabling cells to escape post-mitotic G1 arrest, demonstrating a physiological anti-apoptotic role during mitotic stress.","evidence":"Live-cell imaging, cytochrome c retention and caspase activity assays, overexpression and knockdown in nocodazole-treated human cells","pmids":["36917609"],"confidence":"Medium","gaps":["Whether cytochrome c retention is mediated through cardiolipin maintenance or an independent mechanism not resolved","in vivo relevance during normal mitosis untested"]},{"year":2025,"claim":"Biophysical dissection of TRIAP1 folding revealed that MIA40 accelerates its oxidative maturation 30-fold by directing sequential disulfide formation and bypassing a kinetic trap, explaining how TRIAP1 achieves its native structure in the IMS.","evidence":"NMR, in vitro oxidative folding assays, cysteine mutagenesis, MIA40 interaction assays","pmids":["39909379"],"confidence":"High","gaps":["In vivo folding kinetics and whether other IMS factors assist not determined","how folding couples to PRELI/SLMO2 complex assembly unknown"]},{"year":null,"claim":"Key unresolved questions include the structural basis of the human TRIAP1–PRELI and TRIAP1–SLMO2 complexes, how TRIAP1 partitions between cytosolic and mitochondrial pools to coordinate anti-apoptotic and lipid transfer functions, and the mechanism by which TRIAP1 influences antioxidant gene expression and ER lipid homeostasis.","evidence":"","pmids":[],"confidence":"Low","gaps":["No human TRIAP1 complex structure solved","cytosolic vs. mitochondrial pool regulation mechanism unknown","direct vs. indirect effects on antioxidant protein expression not distinguished"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,3,4,5]},{"term_id":"GO:0140104","term_label":"molecular carrier activity","supporting_discovery_ids":[0,4,5]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,2,7,8]}],"pathway":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[0,1,9,10]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,4,5,13]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[2,8]}],"complexes":["TRIAP1-PRELI (Mdm35-Ups1) PA transfer complex","TRIAP1-SLMO2 (Mdm35-Ups2) PS transfer complex"],"partners":["PRELID1","SLMO2","CHCHD4","HSPA1A"],"other_free_text":[]},"mechanistic_narrative":"TRIAP1 is a small twin CX9C protein of the mitochondrial intermembrane space that functions as an obligate partner of PRELI/SLMO2-family lipid transfer proteins, forming heterodimeric complexes that shuttle phosphatidic acid for cardiolipin synthesis and phosphatidylserine for phosphatidylethanolamine synthesis between mitochondrial membranes [PMID:23931759, PMID:27241913]. TRIAP1 is imported via the MIA40 disulfide relay pathway, which catalyzes sequential oxidation of its two disulfide bonds and overcomes a non-native kinetic folding trap [PMID:39909379]. Loss of TRIAP1 depletes cardiolipin, promotes VDAC oligomerization and cytochrome c release, and activates the APAF1/caspase-9 apoptosome; conversely, TRIAP1 upregulation retains cytochrome c in mitochondria and suppresses apoptosis during mitotic stress [PMID:23931759, PMID:27032384, PMID:36917609, PMID:38157298]. TRIAP1 is also a p53 target gene whose depletion perturbs mitochondrial ultrastructure, ER-dependent lipid homeostasis, and redox balance, linking mitochondrial phospholipid transfer to broader cellular stress responses [PMID:15735003, PMID:36387192, PMID:32096592]."},"prefetch_data":{"uniprot":{"accession":"O43715","full_name":"TP53-regulated inhibitor of apoptosis 1","aliases":["Protein 15E1.1","WF-1","p53-inducible cell-survival factor","p53CSV"],"length_aa":76,"mass_kda":8.8,"function":"Involved in the modulation of the mitochondrial apoptotic pathway by ensuring the accumulation of cardiolipin (CL) in mitochondrial membranes. In vitro, the TRIAP1:PRELID1 complex mediates the transfer of phosphatidic acid (PA) between liposomes and probably functions as a PA transporter across the mitochondrion intermembrane space to provide PA for CL synthesis in the inner membrane (PubMed:23931759). Likewise, the TRIAP1:PRELID3A complex mediates the transfer of phosphatidic acid (PA) between liposomes (in vitro) and probably functions as a PA transporter across the mitochondrion intermembrane space (in vivo) (PubMed:26071602). Mediates cell survival by inhibiting activation of caspase-9 which prevents induction of apoptosis (PubMed:15735003)","subcellular_location":"Mitochondrion; Mitochondrion intermembrane space","url":"https://www.uniprot.org/uniprotkb/O43715/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":true,"resolved_as":"","url":"https://depmap.org/portal/gene/TRIAP1","classification":"Common Essential","n_dependent_lines":1171,"n_total_lines":1208,"dependency_fraction":0.9693708609271523},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"ALDH16A1","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/TRIAP1","total_profiled":1310},"omim":[{"mim_id":"620754","title":"PRELI DOMAIN-CONTAINING PROTEIN 3B; PRELID3B","url":"https://www.omim.org/entry/620754"},{"mim_id":"616545","title":"PRELI DOMAIN-CONTAINING PROTEIN 3A; PRELID3A","url":"https://www.omim.org/entry/616545"},{"mim_id":"614943","title":"TP53-REGULATED INHIBITOR OF APOPTOSIS 1; TRIAP1","url":"https://www.omim.org/entry/614943"},{"mim_id":"605733","title":"PRELI DOMAIN-CONTAINING PROTEIN 1; PRELID1","url":"https://www.omim.org/entry/605733"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Mitochondria","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/TRIAP1"},"hgnc":{"alias_symbol":["P53CSV","WF-1","HSPC132","p53CSV","MDM35"],"prev_symbol":[]},"alphafold":{"accession":"O43715","domains":[{"cath_id":"-","chopping":"5-54","consensus_level":"high","plddt":94.0234,"start":5,"end":54}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O43715","model_url":"https://alphafold.ebi.ac.uk/files/AF-O43715-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O43715-F1-predicted_aligned_error_v6.png","plddt_mean":87.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=TRIAP1","jax_strain_url":"https://www.jax.org/strain/search?query=TRIAP1"},"sequence":{"accession":"O43715","fasta_url":"https://rest.uniprot.org/uniprotkb/O43715.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O43715/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O43715"}},"corpus_meta":[{"pmid":"23931759","id":"PMC_23931759","title":"TRIAP1/PRELI complexes prevent apoptosis by mediating intramitochondrial transport of phosphatidic acid.","date":"2013","source":"Cell metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/23931759","citation_count":167,"is_preprint":false},{"pmid":"20657548","id":"PMC_20657548","title":"Regulation of mitochondrial phospholipids by Ups1/PRELI-like proteins depends on proteolysis and Mdm35.","date":"2010","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/20657548","citation_count":141,"is_preprint":false},{"pmid":"27241913","id":"PMC_27241913","title":"MICOS and phospholipid transfer by Ups2-Mdm35 organize membrane lipid synthesis in mitochondria.","date":"2016","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/27241913","citation_count":128,"is_preprint":false},{"pmid":"27354379","id":"PMC_27354379","title":"Phosphatidylserine transport by Ups2-Mdm35 in respiration-active mitochondria.","date":"2016","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/27354379","citation_count":63,"is_preprint":false},{"pmid":"23684607","id":"PMC_23684607","title":"A genetic screen identifies TCF3/E2A and TRIAP1 as pathway-specific regulators of the cellular response to p53 activation.","date":"2013","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/23684607","citation_count":60,"is_preprint":false},{"pmid":"15735003","id":"PMC_15735003","title":"p53CSV, a novel p53-inducible gene involved in the p53-dependent cell-survival pathway.","date":"2005","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/15735003","citation_count":60,"is_preprint":false},{"pmid":"27428374","id":"PMC_27428374","title":"Overexpression of Mitochondria Mediator Gene TRIAP1 by miR-320b Loss Is Associated with Progression in Nasopharyngeal Carcinoma.","date":"2016","source":"PLoS genetics","url":"https://pubmed.ncbi.nlm.nih.gov/27428374","citation_count":50,"is_preprint":false},{"pmid":"26071601","id":"PMC_26071601","title":"Structural basis of intramitochondrial phosphatidic acid transport mediated by Ups1-Mdm35 complex.","date":"2015","source":"EMBO reports","url":"https://pubmed.ncbi.nlm.nih.gov/26071601","citation_count":48,"is_preprint":false},{"pmid":"19171422","id":"PMC_19171422","title":"SAGE analysis highlights the importance of p53csv, ddx5, mapkapk2 and ranbp2 to multiple myeloma tumorigenesis.","date":"2009","source":"Cancer letters","url":"https://pubmed.ncbi.nlm.nih.gov/19171422","citation_count":44,"is_preprint":false},{"pmid":"25998939","id":"PMC_25998939","title":"Apoptosis inhibitor TRIAP1 is a novel effector of drug resistance.","date":"2015","source":"Oncology reports","url":"https://pubmed.ncbi.nlm.nih.gov/25998939","citation_count":37,"is_preprint":false},{"pmid":"28588697","id":"PMC_28588697","title":"MicroRNA-18a inhibits ovarian cancer growth via directly targeting TRIAP1 and IPMK.","date":"2017","source":"Oncology letters","url":"https://pubmed.ncbi.nlm.nih.gov/28588697","citation_count":34,"is_preprint":false},{"pmid":"33981772","id":"PMC_33981772","title":"Circular RNA circPVT1 Contributes to Doxorubicin (DXR) Resistance of Osteosarcoma Cells by Regulating TRIAP1 via miR-137.","date":"2021","source":"BioMed research international","url":"https://pubmed.ncbi.nlm.nih.gov/33981772","citation_count":28,"is_preprint":false},{"pmid":"30871022","id":"PMC_30871022","title":"Progression-Related Loss of Stromal Caveolin 1 Levels Mediates Radiation Resistance in Prostate Carcinoma via the Apoptosis Inhibitor TRIAP1.","date":"2019","source":"Journal of clinical medicine","url":"https://pubmed.ncbi.nlm.nih.gov/30871022","citation_count":27,"is_preprint":false},{"pmid":"27032384","id":"PMC_27032384","title":"TP53 Regulated Inhibitor of Apoptosis 1 (TRIAP1) stable silencing increases late apoptosis by upregulation of caspase 9 and APAF1 in RPMI8226 multiple myeloma cell line.","date":"2016","source":"Biochimica et biophysica acta","url":"https://pubmed.ncbi.nlm.nih.gov/27032384","citation_count":21,"is_preprint":false},{"pmid":"33123835","id":"PMC_33123835","title":"Regulation of Apoptosis and Inflammatory Response in Interleukin-1β-Induced Nucleus Pulposus Cells by miR-125b-5p Via Targeting TRIAP1.","date":"2020","source":"Biochemical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/33123835","citation_count":17,"is_preprint":false},{"pmid":"35109849","id":"PMC_35109849","title":"PCGEM1 promotes proliferation, migration and invasion in prostate cancer by sponging miR-506 to upregulate TRIAP1.","date":"2022","source":"BMC urology","url":"https://pubmed.ncbi.nlm.nih.gov/35109849","citation_count":16,"is_preprint":false},{"pmid":"31934005","id":"PMC_31934005","title":"miR-107 targets TRIAP1 to regulate oral squamous cell carcinoma proliferation and migration.","date":"2019","source":"International journal of 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Cisplatin.","date":"2019","source":"Chemotherapy","url":"https://pubmed.ncbi.nlm.nih.gov/31661694","citation_count":13,"is_preprint":false},{"pmid":"35480301","id":"PMC_35480301","title":"miR-107 Inhibits the Proliferation of Gastric Cancer Cells In vivo and In vitro by Targeting TRIAP1.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35480301","citation_count":12,"is_preprint":false},{"pmid":"32764987","id":"PMC_32764987","title":"Upregulation of TRIAP1 by the lncRNA MFI2-AS1/miR-125a-5p Axis Promotes Thyroid Cancer Tumorigenesis.","date":"2020","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/32764987","citation_count":11,"is_preprint":false},{"pmid":"38157298","id":"PMC_38157298","title":"CHCHD4-TRIAP1 regulation of innate immune signaling mediates skeletal muscle adaptation to exercise.","date":"2023","source":"Cell 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Society for Experimental Biology and Medicine (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/57624","citation_count":2,"is_preprint":false},{"pmid":"38302925","id":"PMC_38302925","title":"Upregulated microRNA-125b-5p in patients with asthma-COPD overlap mediates oxidative stress and late apoptosis via targeting IL6R/TRIAP1 signaling.","date":"2024","source":"Respiratory research","url":"https://pubmed.ncbi.nlm.nih.gov/38302925","citation_count":1,"is_preprint":false},{"pmid":"40654025","id":"PMC_40654025","title":"SLMO2 inhibits apoptosis in ovarian cancer cells by modulating mitochondrial function via TRIAP1.","date":"2025","source":"Histology and histopathology","url":"https://pubmed.ncbi.nlm.nih.gov/40654025","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":18211,"output_tokens":3668,"usd":0.054827},"stage2":{"model":"claude-opus-4-6","input_tokens":7056,"output_tokens":3274,"usd":0.175695},"total_usd":0.230522,"stage1_batch_id":"msgbatch_01RPbVc9PDH9zQmYK5Hs6srm","stage2_batch_id":"msgbatch_01JVbVLzeKN2yVrsGp3zC8aM","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"TRIAP1 forms a complex with PRELI in the mitochondrial intermembrane space (IMS) and the TRIAP1/PRELI complex exerts lipid transfer activity in vitro, supplying phosphatidic acid (PA) for cardiolipin (CL) synthesis in the inner membrane. Loss of TRIAP1 or PRELI impairs CL accumulation, facilitates cytochrome c release, and renders cells vulnerable to apoptosis.\",\n      \"method\": \"Co-immunoprecipitation, in vitro lipid transfer assay, siRNA knockdown, overexpression, cytochrome c release assay, apoptosis assay with exogenous phosphatidylglycerol rescue\",\n      \"journal\": \"Cell metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstituted lipid transfer activity plus genetic loss-of-function with defined mechanistic readouts; highly cited foundational study\",\n      \"pmids\": [\"23931759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"TRIAP1 (p53CSV) is a p53 target gene that modulates apoptotic pathways through interaction with Hsp70, which inhibits the activity of apoptosis protease activating factor-1 (Apaf-1). Overexpression protected cells from apoptosis after DNA damage, while siRNA-mediated knockdown enhanced apoptosis.\",\n      \"method\": \"siRNA knockdown, overexpression, co-immunoprecipitation with Hsp70, apoptosis assay, p53-binding site identification in gene\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP with Hsp70 and functional knockdown/overexpression assays, single lab\",\n      \"pmids\": [\"15735003\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The yeast TRIAP1 ortholog Mdm35 (a twin Cx9C protein) is a novel interaction partner of Ups1 and Ups2 (PRELI-like proteins) in the IMS. Binding to Mdm35 ensures import and protects Ups1/Ups2 against proteolysis by distinct mitochondrial peptidases (Yme1 for Ups2; Yme1 and Atp23 for Ups1), thereby regulating CL and PE accumulation in mitochondria.\",\n      \"method\": \"Co-immunoprecipitation, proteolysis assays, genetic deletion analysis, import assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (Co-IP, proteolysis, genetics) in foundational yeast ortholog study, highly cited\",\n      \"pmids\": [\"20657548\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Crystal structure of the yeast Ups1-Mdm35 (PRELI-TRIAP1 ortholog) complex with PA bound was solved. Ups1 features a barrel-like structure with a tunnel-like pocket accommodating PA; helix α2 acts as a lid. Mdm35 adopts a three-helical clamp structure wrapping around Ups1. Hydrophobic residues lining the pocket and helix α2 are critical for PA binding and transfer, demonstrated by mutagenesis.\",\n      \"method\": \"X-ray crystallography, in vitro PA-binding assay, lipid transfer assay, site-directed mutagenesis\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure combined with in vitro functional assays and mutagenesis\",\n      \"pmids\": [\"26071601\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"The human SLMO2-TRIAP1 complex (Ups2-Mdm35 in yeast) functions as a phosphatidylserine (PS)-specific lipid transfer protein in the mitochondrial IMS, enabling PE synthesis by the inner membrane decarboxylase Psd1. MICOS deficiency combined with reduced Ups2-Mdm35 PS transfer preserves mitochondrial respiration and cristae formation.\",\n      \"method\": \"Genetic deletion, in vitro lipid transfer assay, mitochondrial fractionation, respiration measurements, electron microscopy\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstituted PS transfer activity plus genetic epistasis with MICOS, multiple orthogonal methods\",\n      \"pmids\": [\"27241913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"A recombinant Ups2-Mdm35 (SLMO2-TRIAP1 ortholog) fusion protein exhibited phospholipid (PS) transfer activity between liposomes in vitro. UPS2/MDM35 null mutations greatly attenuated PS-to-PE conversion in respiration-active yeast, and UPS2 expression was elevated during the diauxic shift.\",\n      \"method\": \"In vitro liposome-based lipid transfer assay, genetic deletion, isotope labeling/PS-to-PE conversion assay\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro lipid transfer reconstitution plus in vivo genetic validation\",\n      \"pmids\": [\"27354379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"In a genome-wide genetic screen, TRIAP1 was identified as a specific repressor of p21 (CDKN1A) expression upon p53 activation; its depletion slows cell-cycle progression without strongly promoting apoptosis, placing TRIAP1 as a pathway-specific coregulator that biases p53 responses toward cell-cycle arrest outcomes.\",\n      \"method\": \"Genome-wide RNAi screen (p21:PUMA ratio readout), siRNA knockdown, flow cytometry cell-cycle analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide functional screen with defined readout, single lab\",\n      \"pmids\": [\"23684607\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Exercise training downregulates the mitochondrial disulfide relay carrier CHCHD4, which decreases import of TRIAP1 into mitochondria. Reduced mitochondrial TRIAP1 lowers cardiolipin levels and promotes VDAC oligomerization, facilitating mtDNA release that activates cGAS-STING/NF-κB innate immune signaling, downregulates MyoD, and drives formation of oxidative slow-twitch muscle fibers. CHCHD4 haploinsufficiency recapitulates this pathway in mice.\",\n      \"method\": \"CHCHD4 haploinsufficiency mouse model, mitochondrial import assays, cardiolipin measurement, VDAC oligomerization assay, cGAS-STING signaling readouts, muscle fiber-type analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal in vivo and cell-based methods establishing pathway position with defined mechanistic readouts\",\n      \"pmids\": [\"38157298\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"TRIAP1 is imported into the IMS via the MIA40 disulfide relay system. In its reduced cytosolic state, TRIAP1 rapidly populates a hydrophobic, alpha-helical molten globule intermediate that creates a non-native Cys37-Cys47 kinetic trap slowing oxidative folding. MIA40 accelerates TRIAP1 folding 30-fold by driving oxidation of the inner disulfide bond (Cys18-Cys37) and then the outer bond (Cys8-Cys47) to achieve the native two-disulfide-bridged structure, bypassing the kinetic trap.\",\n      \"method\": \"NMR, in vitro oxidative folding assays, mutagenesis of cysteines, MIA40 interaction assays, biophysical characterization of folding intermediates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structural/biophysical characterization combined with in vitro reconstitution of MIA40-catalyzed folding and mutagenesis\",\n      \"pmids\": [\"39909379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Stable knockdown of TRIAP1 in RPMI8226 multiple myeloma cells increased late apoptosis accompanied by upregulation of APAF1 and Caspase-9 expression and increased Caspase-9 and Caspase-3/7 activity, establishing that TRIAP1 functions to suppress the APAF1/Caspase-9 apoptosome pathway.\",\n      \"method\": \"Lentiviral shRNA stable knockdown, flow cytometry (annexin V/PI), caspase activity assays, qPCR\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean stable KD with multiple orthogonal apoptosis readouts, single lab\",\n      \"pmids\": [\"27032384\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"Triap1 upregulation in human cells surviving nocodazole-induced prolonged mitotic arrest leads to retention of cytochrome c in the mitochondria, opposing partial caspase activation caused by the drug. Increasing Triap1 levels reduced DNA damage and p21 activation, allowing cells to escape G1 arrest and resume proliferation; decreasing Triap1 re-sensitized cells to nocodazole.\",\n      \"method\": \"Long-term live-cell imaging, cytochrome c retention assay, caspase activity assay, overexpression and knockdown, flow cytometry for DNA damage and p21\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain- and loss-of-function with mechanistic readout (cytochrome c retention, caspase activation), single lab\",\n      \"pmids\": [\"36917609\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"TRIAP1 knockdown in NSCLC cells decreased the expression of antioxidant proteins (TMX1, TMX2, TXN, GLRX2, GLRX3, PRDX3, PRDX4, PRDX6) and impaired radiation-induced upregulation of these proteins, increasing intracellular ROS and sensitizing cells to ionizing radiation, identifying TRIAP1 as a regulator of redox homeostasis.\",\n      \"method\": \"siRNA knockdown, western blotting for antioxidant proteins, ROS measurement, clonogenic survival assay, apoptosis assay\",\n      \"journal\": \"Thoracic cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — knockdown with defined molecular readouts across multiple antioxidant proteins, single lab\",\n      \"pmids\": [\"32096592\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SLMO2 (PRELI) physically interacts with TRIAP1 in ovarian cancer cells; this interaction enhances mitochondrial membrane potential, reduces ROS, inhibits autophagy, and suppresses apoptosis, consistent with the SLMO2-TRIAP1 complex regulating mitochondrial function.\",\n      \"method\": \"Co-immunoprecipitation/interaction assay, flow cytometry (membrane potential, ROS), western blot for autophagy proteins, xenograft tumor model\",\n      \"journal\": \"Histology and histopathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP plus functional assays, single lab, newly published\",\n      \"pmids\": [\"40654025\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"TRIAP1 depletion in colorectal cancer cells perturbs mitochondrial ultrastructure and causes extramitochondrial perturbations including changes in ER-dependent lipid homeostasis and induction of a p53-mediated stress response. Loss of TRIAP1 also confers p53-mediated resistance to glutamine deprivation, demonstrating extramitochondrial functions of TRIAP1.\",\n      \"method\": \"siRNA/shRNA knockdown, electron microscopy, lipidomics, metabolomics, p53 pathway reporter assays, glutamine deprivation survival assays\",\n      \"journal\": \"Frontiers in oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — multiple orthogonal methods revealing extramitochondrial consequences, single lab\",\n      \"pmids\": [\"36387192\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"TRIAP1 (p53CSV) is a p53-induced small IMS protein that forms a complex with PRELI/SLMO2 family members (imported via MIA40-catalyzed disulfide bond formation) to act as an intramitochondrial lipid transfer protein shuttling phosphatidic acid (and, as its homolog Ups2-Mdm35, phosphatidylserine) between mitochondrial membranes for cardiolipin and PE synthesis; loss of TRIAP1 reduces cardiolipin levels, promotes VDAC oligomerization and cytochrome c release, and triggers apoptosis via the APAF1/caspase-9 pathway, while cytosolic TRIAP1 additionally suppresses apoptosome formation through Hsp70 interaction, collectively placing TRIAP1 at the intersection of mitochondrial phospholipid homeostasis and p53-dependent cell survival.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"TRIAP1 is a small twin CX9C protein of the mitochondrial intermembrane space that functions as an obligate partner of PRELI/SLMO2-family lipid transfer proteins, forming heterodimeric complexes that shuttle phosphatidic acid for cardiolipin synthesis and phosphatidylserine for phosphatidylethanolamine synthesis between mitochondrial membranes [PMID:23931759, PMID:27241913]. TRIAP1 is imported via the MIA40 disulfide relay pathway, which catalyzes sequential oxidation of its two disulfide bonds and overcomes a non-native kinetic folding trap [PMID:39909379]. Loss of TRIAP1 depletes cardiolipin, promotes VDAC oligomerization and cytochrome c release, and activates the APAF1/caspase-9 apoptosome; conversely, TRIAP1 upregulation retains cytochrome c in mitochondria and suppresses apoptosis during mitotic stress [PMID:23931759, PMID:27032384, PMID:36917609, PMID:38157298]. TRIAP1 is also a p53 target gene whose depletion perturbs mitochondrial ultrastructure, ER-dependent lipid homeostasis, and redox balance, linking mitochondrial phospholipid transfer to broader cellular stress responses [PMID:15735003, PMID:36387192, PMID:32096592].\",\n  \"teleology\": [\n    {\n      \"year\": 2005,\n      \"claim\": \"Establishing that TRIAP1 is a p53-inducible anti-apoptotic factor answered how cells modulate death sensitivity after DNA damage, revealing that TRIAP1 interacts with Hsp70 to inhibit APAF1-dependent apoptosis.\",\n      \"evidence\": \"Co-immunoprecipitation with Hsp70, siRNA knockdown and overexpression in human cancer cells\",\n      \"pmids\": [\"15735003\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Hsp70 interaction was demonstrated by single Co-IP without reciprocal validation or domain mapping\", \"cytosolic vs. mitochondrial pool contributions to anti-apoptotic effect not distinguished\", \"mechanism by which TRIAP1-Hsp70 inhibits APAF1 not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identification of the yeast ortholog Mdm35 as a binding partner of Ups1/Ups2 that protects them from IMS proteases established the conserved chaperoning function of TRIAP1-family proteins within mitochondria, resolving how PRELI-like proteins are stabilized after import.\",\n      \"evidence\": \"Co-immunoprecipitation, protease sensitivity assays, and genetic deletion in S. cerevisiae\",\n      \"pmids\": [\"20657548\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether human TRIAP1 similarly protects PRELI from degradation was not tested\", \"identity of the relevant human IMS proteases unknown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Reconstitution of phosphatidic acid transfer activity by the TRIAP1–PRELI complex in vitro, coupled with demonstration that loss of either subunit impairs cardiolipin accumulation and sensitizes cells to cytochrome c release, defined the primary molecular function of TRIAP1 as a lipid transfer cofactor essential for cardiolipin biosynthesis.\",\n      \"evidence\": \"In vitro lipid transfer assay, siRNA knockdown, cytochrome c release assay, phosphatidylglycerol rescue in human cells\",\n      \"pmids\": [\"23931759\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether TRIAP1 contributes catalytically to transfer or solely stabilizes PRELI not resolved\", \"structural basis of human complex not determined at this point\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"A genome-wide RNAi screen placed TRIAP1 as a pathway-specific modulator of p53 signaling by showing that its depletion selectively upregulates p21 while sparing PUMA, revealing an unexpected nuclear/cytoplasmic regulatory role beyond mitochondrial lipid transfer.\",\n      \"evidence\": \"Genome-wide RNAi screen with p21:PUMA ratio readout, flow cytometry in human cells\",\n      \"pmids\": [\"23684607\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which TRIAP1 selectively represses p21 not identified\", \"whether this reflects a direct transcriptional role or indirect metabolic consequence unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Solving the crystal structure of the Ups1–Mdm35 complex with bound PA revealed how TRIAP1 wraps around its PRELI partner as a three-helical clamp while a hydrophobic tunnel and lid helix in Ups1 accommodate the lipid cargo, providing the structural basis for lipid specificity.\",\n      \"evidence\": \"X-ray crystallography, mutagenesis, in vitro PA-binding and transfer assays using yeast orthologs\",\n      \"pmids\": [\"26071601\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Human TRIAP1–PRELI structure not yet solved\", \"how membrane association and lipid extraction/insertion occur structurally not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Demonstration that the SLMO2–TRIAP1 (Ups2–Mdm35) complex transfers phosphatidylserine for PE synthesis expanded the functional repertoire of TRIAP1 beyond cardiolipin metabolism, establishing it as a shared cofactor for distinct lipid transfer specificities dictated by the PRELI-family partner.\",\n      \"evidence\": \"In vitro liposome-based PS transfer assay, genetic epistasis with MICOS, isotope labeling in yeast and human cells\",\n      \"pmids\": [\"27241913\", \"27354379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Regulation of partner choice (PRELI vs. SLMO2) not understood\", \"whether additional PRELI-family partners exist for TRIAP1 not addressed\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Stable TRIAP1 knockdown in myeloma cells confirmed that TRIAP1 suppresses the APAF1/caspase-9 intrinsic apoptosis pathway, linking its lipid transfer function to control of the mitochondrial apoptotic cascade.\",\n      \"evidence\": \"Lentiviral shRNA knockdown, caspase-9/3/7 activity assays, APAF1 qPCR in RPMI8226 cells\",\n      \"pmids\": [\"27032384\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether apoptosis sensitization is solely due to cardiolipin loss or also involves cytosolic TRIAP1 functions not distinguished\", \"single cell line\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"TRIAP1 depletion reduced expression of multiple antioxidant proteins and elevated ROS, uncovering a role for TRIAP1 in redox homeostasis that explains its ability to protect cells against ionizing radiation.\",\n      \"evidence\": \"siRNA knockdown, western blotting for TMX1/2, TXN, GLRX2/3, PRDX3/4/6, ROS measurement, clonogenic survival in NSCLC cells\",\n      \"pmids\": [\"32096592\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether redox effects are a direct consequence of impaired cardiolipin/PE metabolism or an independent function is unclear\", \"single cell type, no rescue experiment reported\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Lipidomic and metabolomic profiling of TRIAP1-depleted cells revealed extramitochondrial consequences including altered ER lipid homeostasis and p53-dependent stress responses, broadening the impact of TRIAP1 loss beyond mitochondria.\",\n      \"evidence\": \"siRNA/shRNA knockdown, electron microscopy, lipidomics, metabolomics, glutamine deprivation assays in colorectal cancer cells\",\n      \"pmids\": [\"36387192\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal chain from mitochondrial lipid deficiency to ER perturbation not established\", \"whether extramitochondrial effects reflect a direct ER pool of TRIAP1 unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placing TRIAP1 downstream of CHCHD4/MIA40-dependent import in exercised muscle showed that reduced TRIAP1 import lowers cardiolipin, promotes VDAC oligomerization and mtDNA release, and activates cGAS-STING signaling to drive slow-twitch fiber formation, establishing an in vivo physiological consequence of TRIAP1 regulation.\",\n      \"evidence\": \"CHCHD4 haploinsufficient mice, mitochondrial import assays, cardiolipin measurement, VDAC oligomerization assay, cGAS-STING readouts, muscle fiber-type analysis\",\n      \"pmids\": [\"38157298\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether TRIAP1 is the sole CHCHD4 substrate responsible for the phenotype not proven\", \"applicability beyond skeletal muscle not tested\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"TRIAP1 upregulation during prolonged mitotic arrest was shown to retain cytochrome c in mitochondria and suppress partial caspase activation, enabling cells to escape post-mitotic G1 arrest, demonstrating a physiological anti-apoptotic role during mitotic stress.\",\n      \"evidence\": \"Live-cell imaging, cytochrome c retention and caspase activity assays, overexpression and knockdown in nocodazole-treated human cells\",\n      \"pmids\": [\"36917609\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether cytochrome c retention is mediated through cardiolipin maintenance or an independent mechanism not resolved\", \"in vivo relevance during normal mitosis untested\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Biophysical dissection of TRIAP1 folding revealed that MIA40 accelerates its oxidative maturation 30-fold by directing sequential disulfide formation and bypassing a kinetic trap, explaining how TRIAP1 achieves its native structure in the IMS.\",\n      \"evidence\": \"NMR, in vitro oxidative folding assays, cysteine mutagenesis, MIA40 interaction assays\",\n      \"pmids\": [\"39909379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo folding kinetics and whether other IMS factors assist not determined\", \"how folding couples to PRELI/SLMO2 complex assembly unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis of the human TRIAP1–PRELI and TRIAP1–SLMO2 complexes, how TRIAP1 partitions between cytosolic and mitochondrial pools to coordinate anti-apoptotic and lipid transfer functions, and the mechanism by which TRIAP1 influences antioxidant gene expression and ER lipid homeostasis.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No human TRIAP1 complex structure solved\", \"cytosolic vs. mitochondrial pool regulation mechanism unknown\", \"direct vs. indirect effects on antioxidant protein expression not distinguished\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 3, 4, 5]},\n      {\"term_id\": \"GO:0140104\", \"supporting_discovery_ids\": [0, 4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 2, 7, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [0, 1, 9, 10]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 4, 5, 13]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [2, 8]}\n    ],\n    \"complexes\": [\n      \"TRIAP1-PRELI (Mdm35-Ups1) PA transfer complex\",\n      \"TRIAP1-SLMO2 (Mdm35-Ups2) PS transfer complex\"\n    ],\n    \"partners\": [\n      \"PRELID1\",\n      \"SLMO2\",\n      \"CHCHD4\",\n      \"HSPA1A\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}