{"gene":"CPT2","run_date":"2026-06-09T22:57:19","timeline":{"discoveries":[{"year":1990,"finding":"CPT2 (carnitine palmitoyltransferase from inner mitochondrial membrane) is intrinsically insensitive to malonyl-CoA inhibition, but becomes inhibitable by malonyl-CoA when reconstituted with a malonyl-CoA-binding protein derived from the outer mitochondrial membrane, demonstrating that malonyl-CoA sensitivity requires the outer membrane component.","method":"Reconstitution experiment: cholate-extracted inner and outer mitochondrial membrane fractions combined in vitro; [14C]malonyl-CoA binding assay; CPT activity assay","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro reconstitution with defined fractions, single lab but rigorous biochemical dissection","pmids":["2401367"],"is_preprint":false},{"year":1989,"finding":"CPT2 activity in muscle is distinguishable from CPT1 activity by isotope exchange assay; patients with hepatic CPT1 deficiency (confirmed in fibroblasts) show normal CPT1 and CPT2 activities in muscle, whereas patients with muscular CPT2 deficiency show marked absolute deficiency (<12% residual) of CPT2 in muscle, supporting that CPT1 and CPT2 are separate proteins and that CPT1 may exist as tissue-specific isoforms.","method":"Isotope exchange assay differentiating CPT1 and CPT2 activities in muscle biopsies; kinetic analysis with varying carnitine and palmitoyl-CoA concentrations","journal":"Journal of the neurological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct enzymatic assay in patient tissues with kinetic dissection; single lab, multiple patient samples","pmids":["2809620"],"is_preprint":false},{"year":1998,"finding":"Missense mutations E174K and F383Y in CPT2 markedly decrease catalytic activity of the enzyme, as demonstrated by transfection of mutant constructs in COS-1 cells; a polymorphism F352C does not alter CPT2 activity. Genotype-phenotype correlations show homozygous F383Y causes hepatic phenotype and homozygous E174K causes muscular phenotype.","method":"Site-directed mutagenesis; transfection of mutant CPT2 cDNA in COS-1 cells; enzymatic activity assay","journal":"Human mutation","confidence":"Medium","confidence_rationale":"Tier 1 / Moderate — in vitro mutagenesis with functional activity readout in transfected cells; single lab","pmids":["9600456"],"is_preprint":false},{"year":2019,"finding":"Low-level palmitate activates CDK1, which phosphorylates SIRT3; SIRT3 in turn deacetylates CPT2 and promotes CPT2 dimerization, enhancing fatty acid oxidation and mitochondrial homeostasis in liver cells.","method":"CDK1 kinase assay; SIRT3 deacetylase assay; co-immunoprecipitation; acetylation state analysis of CPT2; CPT2 dimerization assay; in vivo mouse model with CCl4 hepatotoxicity","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple biochemical assays (kinase, deacetylase, dimerization) in single lab; in vitro and in vivo validation","pmids":["31866205"],"is_preprint":false},{"year":2020,"finding":"HRD1 (an E3 ubiquitin ligase) directly ubiquitinates CPT2 via K48-linked ubiquitination, stabilizing CPT2 protein and thereby supporting fatty acid oxidation in triple-negative breast cancer cells; HRD1 expression is downregulated under glutamine deprivation, reducing CPT2 stability.","method":"Co-immunoprecipitation; ubiquitination assay; K48-linkage-specific ubiquitin detection; CPT2 protein stability assays; knockdown/overexpression in TNBC cell lines in vitro and in vivo","journal":"Molecular oncology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and ubiquitination linkage assay; single lab, multiple orthogonal methods","pmids":["33207079"],"is_preprint":false},{"year":2021,"finding":"E2F2 binds directly to the Cpt2 promoter and transcriptionally represses CPT2 expression in the context of NAFLD-related hepatocarcinogenesis; E2f2 knockout in mice enhances fatty acid oxidation and increases CPT2 expression, while E2f2 overexpression elicits opposing effects.","method":"Chromatin immunoprecipitation (ChIP) showing E2F2 binding to Cpt2 promoter; E2f1-/- and E2f2-/- mouse models; E2f2 liver-specific knockdown and overexpression; FAO flux measurements","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — ChIP demonstrating direct promoter binding plus genetic KO and OE models; single lab, multiple orthogonal approaches","pmids":["33771899"],"is_preprint":false},{"year":2022,"finding":"CPT2 acetylation at K79 (caused by NAD+ depletion and reduced SIRT3 activity) attenuates fatty acid oxidation and promotes accumulation of long-chain acylcarnitines, leading to mitochondrial damage and platelet storage lesion; SIRT3 agonists or antioxidants reverse this effect.","method":"Acetylation site identification; SIRT3 activity assays; fatty acid oxidation flux measurements; mitochondrial function assays; in vitro platelet storage and in vivo transfusion models","journal":"Blood advances","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific acetylation site identified with functional FAO readout and in vivo rescue; single lab","pmids":["35728063"],"is_preprint":false},{"year":2024,"finding":"SIRT5, a lysine de-succinylase, de-succinylates CPT2 at Lys424; succinylation of K424 inactivates CPT2 enzymatic activity, impairing conversion of fatty acyl-carnitines to fatty acyl-CoA. Sirt5 deficiency increases K424 succinylation and causes accumulation of medium- and long-chain fatty acyl-carnitines. CPT2 K424R mutation (mimicking de-succinylation) rescues enzymatic activity and FAO impairment in Sirt5-KO hearts.","method":"Succinylomics proteomics; site-specific mutagenesis (K424R); CPT2 enzymatic activity assay; acylcarnitine metabolomics; Sirt5 KO and overexpression in diabetic mouse model; FAO flux measurement","journal":"Redox biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — succinylomics identification, mutagenesis validation, enzymatic activity assay, and in vivo rescue in multiple models; multiple orthogonal methods","pmids":["38718533"],"is_preprint":false},{"year":2025,"finding":"SIRT2, localized to cardiac mitochondria, deacetylates CPT2 at K239; this deacetylation promotes CPT2 ubiquitination, decreasing CPT2 protein stability and thereby inhibiting fatty acid oxidation and ROS production in the diabetic heart.","method":"Co-immunoprecipitation; deacetylation assay; K239 acetylation site identification; ubiquitination assay; CPT2 protein stability measurement; SIRT2 cardiac-specific overexpression/knockdown in STZ/HFD mouse model","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific acetylation site with functional stability readout and in vivo model; single lab, multiple methods","pmids":["39781464"],"is_preprint":false},{"year":2022,"finding":"FAM3A promotes transcription of CPT2 through a signaling cascade: FAM3A-induced ATP release activates P2 receptors, promoting nuclear translocation of calmodulin (CaM), which acts as a co-activator of FOXA2 to drive CPT2 promoter activity and increase fatty acid oxidation.","method":"RNA sequencing; FOXA2 ChIP/promoter assay; CaM nuclear translocation imaging; CPT2 mRNA/protein measurement; FAM3A-deficient hepatocytes and mice; imipramine pharmacology","journal":"Metabolism: clinical and experimental","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pathway placed by epistasis (FAM3A KO abrogates CaM-FOXA2-CPT2 activation) with multiple orthogonal methods; single lab","pmids":["35995281"],"is_preprint":false},{"year":2020,"finding":"Pharmacological inhibition of CPT2-dependent FAO (by aminocarnitine) in LPS-induced endotoxaemia causes accumulation of long-chain acylcarnitines, inhibits cardiac pyruvate metabolism, and exacerbates inflammation-induced cardiac dysfunction, demonstrating that CPT2 activity is required to prevent acylcarnitine-mediated mitochondrial dysfunction.","method":"Pharmacological CPT2 inhibition with aminocarnitine in vivo; cardiac mitochondrial respiration; acylcarnitine metabolite quantification; cardiac function measurement","journal":"Journal of cellular and molecular medicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — specific inhibitor with mechanistic metabolite and functional readouts in vivo; single lab","pmids":["32896106"],"is_preprint":false},{"year":2025,"finding":"SIRT3 interacts with CPT2 and stabilizes the CPT2 protein by mediating de-lactylation of CPT2, prolonging its half-life and preventing its degradation; CPT2 overexpression enhances fatty acid β-oxidation and promotes granulosa cell proliferation via increased β-catenin and cyclin D1 levels.","method":"Co-immunoprecipitation (SIRT3-CPT2 interaction); CPT2 protein half-life measurement; lactylation/de-lactylation assay; CPT2 overexpression in goat granulosa cells; FAO and mitochondrial function assays","journal":"Journal of animal science and biotechnology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus PTM (lactylation) functional assay and half-life measurement; single lab, orthogonal methods","pmids":["40671144"],"is_preprint":false},{"year":2025,"finding":"MUL1 (mitochondrial E3 ubiquitin ligase 1) promotes ubiquitin-mediated degradation of CPT2; SLC44A2 enhances the interaction between MUL1 and CPT2 (without increasing MUL1 expression), facilitating CPT2 degradation and inhibiting mitochondrial fatty acid oxidation.","method":"Co-immunoprecipitation (MUL1-CPT2 interaction); CPT2 protein stability/ubiquitination assays; SLC44A2 overexpression/knockdown; FAO flux measurements in CRC cells in vitro and in vivo","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP demonstrating protein interaction with ubiquitination and stability readout; single lab, multiple orthogonal approaches","pmids":["40592838"],"is_preprint":false},{"year":2025,"finding":"SLC25A42 (mitochondrial CoA transporter) upregulates CPT2 acetylation and thereby increases CPT2 expression and activity, reprogramming lipid metabolism to enhance fatty acid oxidation-mediated mitochondrial respiration and reduce ferroptosis in gastric cancer cells.","method":"CPT2 acetylation analysis; co-immunoprecipitation; FAO flux (Seahorse); ROS and free fatty acid measurements; SLC25A42 KD/OE in vitro and in vivo","journal":"Cell death & disease","confidence":"Low","confidence_rationale":"Tier 3 / Weak — acetylation link to CPT2 reported but mechanistic detail thin in abstract; single lab, limited methodological detail","pmids":["40246810"],"is_preprint":false},{"year":2018,"finding":"AMPK activation by GSK773 upregulates CPT2 protein expression in CPT2-deficient patient myotubes, correcting deficient FAO flux and acylcarnitine accumulation; effects are mediated through PGC-1α, ROS, and p38 MAPK pathways; AMPK is constitutively activated in CPT2-deficient myotubes.","method":"Patient-derived myotubes with CPT2 mutations; FAO flux assay; acylcarnitine profiling; CPT2 protein quantification; siRNA knockdowns; pharmacological inhibitors; mitochondrial biogenesis markers","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — human patient-derived cells with multiple metabolic and genetic perturbations; single lab","pmids":["30007356"],"is_preprint":false},{"year":2024,"finding":"CPT2-mediated long-chain fatty acid oxidation is dispensable for B cell development, activation, germinal center formation, and antibody production; stable 13C isotope tracing confirms CPT2 deficiency abolishes fatty acid-derived citrate production in B cells, yet humoral immunity is unaffected.","method":"Lymphocyte-specific CPT2 knockout mouse; stable [13C] isotope tracing of fatty acid-derived citrate; B cell developmental and functional assays (FACS, GC formation, Ab titers)","journal":"Journal of immunology","confidence":"High","confidence_rationale":"Tier 1 / Strong — genetic KO with isotope tracing and comprehensive immune phenotyping; negative mechanistic finding well-established","pmids":["39258879"],"is_preprint":false},{"year":2022,"finding":"CPT2 R631C mutation leads to reduced fluorescence intensity compared to wild-type when expressed in cells (suggesting increased protein degradation), and reduces the ability of CPT2 to bind UCP2, without altering subcellular localization.","method":"Fluorescence intensity measurement of WT vs. mutant CPT2 in transfected cells; co-immunoprecipitation/interaction assay with UCP2; localization imaging","journal":"Frontiers in cell and developmental biology","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, limited mechanistic follow-up from WES study; interaction with UCP2 shown by single method","pmids":["35372350"],"is_preprint":false}],"current_model":"CPT2 encodes the inner mitochondrial membrane enzyme carnitine palmitoyltransferase II, which converts fatty acyl-carnitines back to fatty acyl-CoA to enable mitochondrial β-oxidation; its activity is intrinsically malonyl-CoA-insensitive but can be regulated by the outer membrane malonyl-CoA-binding protein, and is controlled post-translationally by multiple sirtuins—SIRT5 de-succinylates K424 to activate it, SIRT3 deacetylates and dimerizes it (and de-lactylates it to stabilize it), and SIRT2 deacetylates K239 to promote its ubiquitination and degradation—while transcriptional repressors E2F1/E2F2 and a FAM3A-CaM-FOXA2 axis regulate its expression, and E3 ligases HRD1 (stabilizing K48-ubiquitination) and MUL1 (degradative ubiquitination, enhanced by SLC44A2) control its protein stability, together making CPT2 a nexus for fatty acid oxidation regulation in heart, liver, muscle, and immune cells."},"narrative":{"mechanistic_narrative":"CPT2 encodes the inner mitochondrial membrane carnitine palmitoyltransferase that reconverts fatty acyl-carnitines to fatty acyl-CoA, the committed step enabling mitochondrial long-chain fatty acid β-oxidation [PMID:2401367, PMID:38718533]. Unlike the outer-membrane CPT1, CPT2 is intrinsically insensitive to malonyl-CoA and acquires this sensitivity only when reconstituted with an outer-membrane malonyl-CoA-binding component, establishing it as a topologically and functionally distinct enzyme [PMID:2401367, PMID:2809620]. Catalytic activity depends on intact active-site architecture, as disease-associated missense substitutions (E174K, F383Y) sharply reduce activity and segregate with muscular versus hepatic clinical phenotypes, defining CPT2 as the gene underlying carnitine palmitoyltransferase II deficiency [PMID:9600456, PMID:30007356]. CPT2 is a major node for post-translational control of fatty acid oxidation through reversible lysine acylation: SIRT5 de-succinylates K424 to relieve succinylation-mediated inactivation [PMID:38718533], SIRT3 deacetylates the enzyme to promote its catalytically active dimer [PMID:31866205], and acetylation at K79 conversely suppresses oxidation and drives long-chain acylcarnitine accumulation [PMID:35728063]. Protein abundance is set by competing ubiquitin ligases—HRD1 stabilizes CPT2 via K48-linked ubiquitination to sustain oxidation, while MUL1, aided by SLC44A2, drives its degradation, and SIRT2-mediated K239 deacetylation promotes its ubiquitin-dependent turnover [PMID:33207079, PMID:40592838, PMID:39781464]. At the transcriptional level CPT2 is repressed by E2F2 and induced through a FAM3A–calmodulin–FOXA2 axis [PMID:33771899, PMID:35995281]. Functionally, loss of CPT2 activity causes accumulation of long-chain acylcarnitines and mitochondrial dysfunction across heart, liver, muscle, and platelets, whereas its activity is dispensable for B-cell development and humoral immunity [PMID:32896106, PMID:35728063, PMID:39258879].","teleology":[{"year":1989,"claim":"Established that CPT2 is a protein biochemically and genetically separable from CPT1, resolving whether muscle and liver carnitine palmitoyltransferase deficiencies arise from distinct enzymes.","evidence":"Isotope exchange enzymatic assays distinguishing CPT1 and CPT2 activities in patient muscle biopsies and fibroblasts","pmids":["2809620"],"confidence":"Medium","gaps":["Did not define the molecular basis of the residual activity or the gene sequence","Tissue-specific CPT1 isoform hypothesis not resolved at the protein level"]},{"year":1990,"claim":"Defined the topological logic of malonyl-CoA regulation by showing CPT2 is intrinsically malonyl-CoA-insensitive and only acquires sensitivity from an outer-membrane binding partner.","evidence":"In vitro reconstitution of cholate-extracted inner and outer mitochondrial membrane fractions with malonyl-CoA binding and CPT activity assays","pmids":["2401367"],"confidence":"High","gaps":["Molecular identity of the malonyl-CoA-binding outer-membrane component not defined here","Stoichiometry and physical interaction with CPT2 not mapped"]},{"year":1998,"claim":"Connected specific missense mutations to loss of catalytic activity and to genotype-phenotype correlation, establishing CPT2 as the causal gene for carnitine palmitoyltransferase II deficiency.","evidence":"Site-directed mutagenesis of CPT2 with expression and enzymatic activity assays in COS-1 cells","pmids":["9600456"],"confidence":"Medium","gaps":["No structural explanation of how E174K/F383Y impair catalysis","Mechanism linking specific mutations to hepatic vs muscular tissue phenotype unresolved"]},{"year":2018,"claim":"Showed that CPT2-deficient FAO can be pharmacologically corrected by raising CPT2 protein, opening a therapeutic route in patient cells.","evidence":"AMPK activator (GSK773) treatment of CPT2-mutant patient-derived myotubes with FAO flux, acylcarnitine profiling, and pathway perturbation","pmids":["30007356"],"confidence":"Medium","gaps":["Whether correction depends on mutant residual activity vs increased abundance not separated","PGC-1α/ROS/p38 contributions defined only pharmacologically"]},{"year":2019,"claim":"Identified deacetylation as an activating switch by showing a palmitate-CDK1-SIRT3 cascade deacetylates CPT2 and drives its active dimer.","evidence":"Kinase and deacetylase assays, co-IP, acetylation and dimerization analysis in liver cells plus a CCl4 mouse model","pmids":["31866205"],"confidence":"Medium","gaps":["Specific deacetylated lysines not mapped in this study","Quantitative link between dimerization and catalytic rate not established"]},{"year":2020,"claim":"Demonstrated that ubiquitination can stabilize rather than degrade CPT2, linking metabolic stress to CPT2 abundance via HRD1.","evidence":"Reciprocal co-IP, K48-linkage-specific ubiquitination and stability assays in TNBC cells in vitro and in vivo","pmids":["33207079"],"confidence":"Medium","gaps":["Ubiquitinated lysine residues on CPT2 not mapped","How K48 chains stabilize rather than target CPT2 mechanistically unexplained"]},{"year":2020,"claim":"Established physiologically that CPT2 flux is required to clear long-chain acylcarnitines and protect mitochondrial and cardiac function during inflammation.","evidence":"Pharmacological CPT2 inhibition (aminocarnitine) in LPS endotoxaemia with cardiac respiration, acylcarnitine, and function readouts","pmids":["32896106"],"confidence":"Medium","gaps":["Inhibitor specificity for CPT2 not orthogonally confirmed genetically","Direct toxicity mechanism of accumulated acylcarnitines not dissected"]},{"year":2021,"claim":"Placed CPT2 under direct transcriptional repression by E2F2 in the fatty-liver-to-cancer transition.","evidence":"ChIP showing E2F2 binding to the Cpt2 promoter with E2f2 knockout, knockdown, and overexpression mouse models and FAO flux","pmids":["33771899"],"confidence":"Medium","gaps":["E2F1 contribution relative to E2F2 not fully separated","Coregulators at the Cpt2 promoter not identified"]},{"year":2022,"claim":"Defined an inhibitory acetylation site (K79) whose accumulation under NAD+/SIRT3 decline causes acylcarnitine buildup and organelle damage.","evidence":"Acetylation site identification, SIRT3 activity and FAO flux assays in platelet storage and transfusion models","pmids":["35728063"],"confidence":"Medium","gaps":["Whether K79 acetylation alters catalysis directly vs via stability not resolved","Acetyltransferase responsible for K79 not identified"]},{"year":2022,"claim":"Mapped a transcriptional activation route to CPT2 through a FAM3A-ATP-P2 receptor-calmodulin-FOXA2 signaling axis.","evidence":"RNA-seq, FOXA2 ChIP/promoter assay, CaM nuclear translocation imaging in FAM3A-deficient hepatocytes and mice","pmids":["35995281"],"confidence":"Medium","gaps":["Direct FOXA2 binding to the CPT2 promoter vs indirect effect not fully distinguished","Which P2 receptor subtype mediates the signal not pinned down"]},{"year":2022,"claim":"Linked a CPT2 variant (R631C) to reduced protein abundance and loss of a UCP2 interaction without altered localization.","evidence":"Fluorescence intensity comparison of WT vs mutant CPT2, co-IP with UCP2, and localization imaging in transfected cells","pmids":["35372350"],"confidence":"Low","gaps":["UCP2 interaction shown by a single method without reciprocal or endogenous validation","Functional consequence of lost UCP2 binding for FAO not measured"]},{"year":2024,"claim":"Identified succinylation at K424 as an inactivating modification reversed by SIRT5, establishing a desuccinylation-dependent activity switch validated by mutational rescue.","evidence":"Succinylomics, K424R mutagenesis, enzymatic activity and acylcarnitine metabolomics with Sirt5 KO/overexpression diabetic mouse models","pmids":["38718533"],"confidence":"High","gaps":["Succinyltransferase or non-enzymatic source of K424 succinylation not defined","Structural basis for K424 succinylation-induced inactivation not solved"]},{"year":2024,"claim":"Showed CPT2-dependent long-chain FAO is dispensable for humoral immunity, delimiting where CPT2 function is metabolically required.","evidence":"Lymphocyte-specific CPT2 knockout mice with 13C isotope tracing and comprehensive B-cell developmental and functional assays","pmids":["39258879"],"confidence":"High","gaps":["Whether other immune lineages depend on CPT2 not addressed","Compensatory metabolic pathways in B cells not characterized"]},{"year":2025,"claim":"Expanded the SIRT3-CPT2 relationship to a de-lactylation mechanism that stabilizes CPT2 and links FAO to granulosa cell proliferation.","evidence":"Co-IP, half-life measurement, lactylation/de-lactylation and FAO assays with CPT2 overexpression in goat granulosa cells","pmids":["40671144"],"confidence":"Medium","gaps":["Lactylated residues on CPT2 not mapped","Causal link between CPT2 stabilization and β-catenin/cyclin D1 induction not mechanistically traced"]},{"year":2025,"claim":"Defined SIRT2 as a deacetylase that destabilizes CPT2 by promoting K239-dependent ubiquitination, showing deacetylation can reduce rather than increase CPT2 function.","evidence":"Co-IP, K239 acetylation site identification, deacetylation and ubiquitination assays with cardiac-specific SIRT2 manipulation in diabetic mice","pmids":["39781464"],"confidence":"Medium","gaps":["Ubiquitin ligase coupling K239 deacetylation to degradation not identified","Reconciliation with SIRT3 activating deacetylation at other residues not addressed"]},{"year":2025,"claim":"Identified MUL1 as a degradative E3 ligase for CPT2 whose action is potentiated by SLC44A2, providing a mitochondrial route to suppress FAO.","evidence":"Co-IP, ubiquitination and stability assays with SLC44A2 manipulation and FAO flux in colorectal cancer cells in vitro and in vivo","pmids":["40592838"],"confidence":"Medium","gaps":["MUL1-ubiquitinated lysines on CPT2 not mapped","How SLC44A2 enhances the MUL1-CPT2 interaction structurally unknown"]},{"year":2025,"claim":"Linked the mitochondrial CoA transporter SLC25A42 to increased CPT2 acetylation, expression and FAO with reduced ferroptosis in gastric cancer.","evidence":"CPT2 acetylation analysis, co-IP, Seahorse FAO flux, and ROS/free fatty acid measurements with SLC25A42 KD/OE","pmids":["40246810"],"confidence":"Low","gaps":["Mechanistic detail of how acetylation increases CPT2 activity here is thin and not site-resolved","Apparent activation by acetylation conflicts with inactivating acetylation reports and is unreconciled"]},{"year":null,"claim":"It remains unresolved how the competing acylation marks (succinylation, acetylation at distinct lysines, lactylation) and opposing ubiquitin ligases are integrated to set net CPT2 activity and abundance in a given tissue.","evidence":"No single study in the corpus reconciles the divergent PTM and stability mechanisms","pmids":[],"confidence":"Medium","gaps":["No unified structural model of how lysine modifications at K79, K239, K424 jointly control catalysis and turnover","Cross-talk between HRD1 stabilization and MUL1/SIRT2 degradation not mapped","Identity of the malonyl-CoA-binding outer-membrane partner from the original reconstitution remains undefined in the corpus"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,2,7]},{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,7]}],"localization":[{"term_id":"GO:0005739","term_label":"mitochondrion","supporting_discovery_ids":[0,8]}],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,7,10,15]}],"complexes":[],"partners":["SIRT3","SIRT5","SIRT2","HRD1","MUL1","SLC44A2","UCP2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P23786","full_name":"Carnitine O-palmitoyltransferase 2, mitochondrial","aliases":["Carnitine palmitoyltransferase II","CPT II"],"length_aa":658,"mass_kda":73.8,"function":"Involved in the intramitochondrial synthesis of acylcarnitines from accumulated acyl-CoA metabolites (PubMed:20538056, PubMed:24780397). Reconverts acylcarnitines back into the respective acyl-CoA esters that can then undergo beta-oxidation, an essential step for the mitochondrial uptake of long-chain fatty acids and their subsequent beta-oxidation in the mitochondrion. Active with medium (C8-C12) and long-chain (C14-C18) acyl-CoA esters (PubMed:20538056)","subcellular_location":"Mitochondrion inner membrane","url":"https://www.uniprot.org/uniprotkb/P23786/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CPT2","classification":"Not Classified","n_dependent_lines":21,"n_total_lines":1208,"dependency_fraction":0.0173841059602649},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CPT2","total_profiled":1310},"omim":[{"mim_id":"614480","title":"HYPERTRIGLYCERIDEMIA, TRANSIENT INFANTILE; HTGTI","url":"https://www.omim.org/entry/614480"},{"mim_id":"614212","title":"ENCEPHALOPATHY, ACUTE, INFECTION-INDUCED, SUSCEPTIBILITY TO, 4; IIAE4","url":"https://www.omim.org/entry/614212"},{"mim_id":"610551","title":"ENCEPHALOPATHY, ACUTE, INFECTION-INDUCED (HERPES-SPECIFIC), SUSCEPTIBILITY TO, 1; IIAE1","url":"https://www.omim.org/entry/610551"},{"mim_id":"609016","title":"LONG-CHAIN 3-HYDROXYACYL-CoA DEHYDROGENASE DEFICIENCY","url":"https://www.omim.org/entry/609016"},{"mim_id":"608836","title":"CARNITINE PALMITOYLTRANSFERASE II DEFICIENCY, LETHAL NEONATAL","url":"https://www.omim.org/entry/608836"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Nucleoplasm","reliability":"Approved"},{"location":"Mitochondria","reliability":"Approved"},{"location":"Nucleoli","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"liver","ntpm":85.2}],"url":"https://www.proteinatlas.org/search/CPT2"},"hgnc":{"alias_symbol":["CPTASE"],"prev_symbol":["CPT1"]},"alphafold":{"accession":"P23786","domains":[{"cath_id":"3.30.559.70","chopping":"130-168_217-438","consensus_level":"high","plddt":97.6689,"start":130,"end":438},{"cath_id":"3.30.559.10","chopping":"441-651","consensus_level":"high","plddt":97.203,"start":441,"end":651}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P23786","model_url":"https://alphafold.ebi.ac.uk/files/AF-P23786-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P23786-F1-predicted_aligned_error_v6.png","plddt_mean":94.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CPT2","jax_strain_url":"https://www.jax.org/strain/search?query=CPT2"},"sequence":{"accession":"P23786","fasta_url":"https://rest.uniprot.org/uniprotkb/P23786.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P23786/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P23786"}},"corpus_meta":[{"pmid":"38718533","id":"PMC_38718533","title":"Sirt5 improves cardiomyocytes fatty acid metabolism and ameliorates cardiac lipotoxicity in diabetic cardiomyopathy via CPT2 de-succinylation.","date":"2024","source":"Redox biology","url":"https://pubmed.ncbi.nlm.nih.gov/38718533","citation_count":75,"is_preprint":false},{"pmid":"29872321","id":"PMC_29872321","title":"Downregulation of CPT2 promotes tumorigenesis and chemoresistance to cisplatin in hepatocellular carcinoma.","date":"2018","source":"OncoTargets and therapy","url":"https://pubmed.ncbi.nlm.nih.gov/29872321","citation_count":59,"is_preprint":false},{"pmid":"33771899","id":"PMC_33771899","title":"E2F1 and E2F2-Mediated Repression of CPT2 Establishes a Lipid-Rich Tumor-Promoting Environment.","date":"2021","source":"Cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/33771899","citation_count":58,"is_preprint":false},{"pmid":"16996287","id":"PMC_16996287","title":"Identification of 16 new disease-causing mutations in the CPT2 gene resulting in carnitine palmitoyltransferase II deficiency.","date":"2006","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/16996287","citation_count":55,"is_preprint":false},{"pmid":"31866205","id":"PMC_31866205","title":"Low-Level Saturated Fatty Acid Palmitate Benefits Liver Cells by Boosting Mitochondrial Metabolism via CDK1-SIRT3-CPT2 Cascade.","date":"2019","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/31866205","citation_count":51,"is_preprint":false},{"pmid":"9600456","id":"PMC_9600456","title":"Two CPT2 mutations in three Japanese patients with carnitine palmitoyltransferase II deficiency: functional analysis and association with polymorphic haplotypes and two clinical phenotypes.","date":"1998","source":"Human mutation","url":"https://pubmed.ncbi.nlm.nih.gov/9600456","citation_count":47,"is_preprint":false},{"pmid":"2809620","id":"PMC_2809620","title":"Normal muscle CPT1 and CPT2 activities in hepatic presentation patients with CPT1 deficiency in fibroblasts. Tissue specific isoforms of CPT1?","date":"1989","source":"Journal of the neurological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/2809620","citation_count":44,"is_preprint":false},{"pmid":"18550408","id":"PMC_18550408","title":"CPT2 gene mutations resulting in lethal neonatal or severe infantile carnitine palmitoyltransferase II deficiency.","date":"2008","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/18550408","citation_count":43,"is_preprint":false},{"pmid":"33207079","id":"PMC_33207079","title":"HRD1 inhibits fatty acid oxidation and tumorigenesis by ubiquitinating CPT2 in triple-negative breast cancer.","date":"2020","source":"Molecular oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33207079","citation_count":41,"is_preprint":false},{"pmid":"35108639","id":"PMC_35108639","title":"Downregulation of CPT2 promotes proliferation and inhibits apoptosis through p53 pathway in colorectal cancer.","date":"2022","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/35108639","citation_count":37,"is_preprint":false},{"pmid":"33486313","id":"PMC_33486313","title":"CPT2 down-regulation promotes tumor growth and metastasis through inducing ROS/NFκB pathway in ovarian cancer.","date":"2021","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33486313","citation_count":33,"is_preprint":false},{"pmid":"34688609","id":"PMC_34688609","title":"CPT2 downregulation triggers stemness and oxaliplatin resistance in colorectal cancer via activating the ROS/Wnt/β-catenin-induced glycolytic metabolism.","date":"2021","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/34688609","citation_count":31,"is_preprint":false},{"pmid":"37541641","id":"PMC_37541641","title":"CPT2-mediated fatty acid oxidation inhibits tumorigenesis and enhances sorafenib sensitivity via the ROS/PPARγ/NF-κB pathway in clear cell renal cell carcinoma.","date":"2023","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/37541641","citation_count":28,"is_preprint":false},{"pmid":"9680378","id":"PMC_9680378","title":"Chromosomal locations of the mouse fatty acid oxidation genes Cpt1a, Cpt1b, Cpt2, Acadvl, and metabolically related Crat gene.","date":"1998","source":"Mammalian genome : official journal of the International Mammalian Genome Society","url":"https://pubmed.ncbi.nlm.nih.gov/9680378","citation_count":23,"is_preprint":false},{"pmid":"2401367","id":"PMC_2401367","title":"Carnitine palmitoyltransferase (CPT2) from liver mitochondrial inner membrane becomes inhibitable by malonyl-CoA if reconstituted with outer membrane malonyl-CoA binding protein.","date":"1990","source":"FEBS letters","url":"https://pubmed.ncbi.nlm.nih.gov/2401367","citation_count":22,"is_preprint":false},{"pmid":"32896106","id":"PMC_32896106","title":"Inhibition of CPT2 exacerbates cardiac dysfunction and inflammation in experimental endotoxaemia.","date":"2020","source":"Journal of cellular and molecular medicine","url":"https://pubmed.ncbi.nlm.nih.gov/32896106","citation_count":20,"is_preprint":false},{"pmid":"35728063","id":"PMC_35728063","title":"CPT2 K79 acetylation regulates platelet life span.","date":"2022","source":"Blood advances","url":"https://pubmed.ncbi.nlm.nih.gov/35728063","citation_count":18,"is_preprint":false},{"pmid":"34059398","id":"PMC_34059398","title":"Recurrent acute necrotizing encephalopathy in a boy with RANBP2 mutation and thermolabile CPT2 variant: The first case of ANE1 in Japan.","date":"2021","source":"Brain & development","url":"https://pubmed.ncbi.nlm.nih.gov/34059398","citation_count":17,"is_preprint":false},{"pmid":"35995281","id":"PMC_35995281","title":"Imipramine activates FAM3A-FOXA2-CPT2 pathway to ameliorate hepatic steatosis.","date":"2022","source":"Metabolism: clinical and experimental","url":"https://pubmed.ncbi.nlm.nih.gov/35995281","citation_count":16,"is_preprint":false},{"pmid":"29478820","id":"PMC_29478820","title":"Fluxomic assay-assisted diagnosis orientation in a cohort of 11 patients with myopathic form of CPT2 deficiency.","date":"2018","source":"Molecular genetics and metabolism","url":"https://pubmed.ncbi.nlm.nih.gov/29478820","citation_count":15,"is_preprint":false},{"pmid":"39781464","id":"PMC_39781464","title":"Mitochondrial SIRT2-mediated CPT2 deacetylation prevents diabetic cardiomyopathy by impeding cardiac fatty acid oxidation.","date":"2025","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/39781464","citation_count":12,"is_preprint":false},{"pmid":"23566841","id":"PMC_23566841","title":"Single nucleotide polymorphism in CPT1B and CPT2 genes and its association with blood carnitine levels in acute myocardial infarction patients.","date":"2013","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/23566841","citation_count":11,"is_preprint":false},{"pmid":"30007356","id":"PMC_30007356","title":"A new AMPK activator, GSK773, corrects fatty acid oxidation and differentiation defect in CPT2-deficient myotubes.","date":"2018","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30007356","citation_count":10,"is_preprint":false},{"pmid":"39258879","id":"PMC_39258879","title":"CPT2-mediated Fatty Acid Oxidation Is Dispensable for Humoral Immunity.","date":"2024","source":"Journal of immunology (Baltimore, Md. : 1950)","url":"https://pubmed.ncbi.nlm.nih.gov/39258879","citation_count":9,"is_preprint":false},{"pmid":"38428407","id":"PMC_38428407","title":"GBA3 promotes fatty acid oxidation and alleviates non-alcoholic fatty liver by increasing CPT2 transcription.","date":"2024","source":"Aging","url":"https://pubmed.ncbi.nlm.nih.gov/38428407","citation_count":9,"is_preprint":false},{"pmid":"36467025","id":"PMC_36467025","title":"Activation of EP4 alleviates AKI-to-CKD transition through inducing CPT2-mediated lipophagy in renal macrophages.","date":"2022","source":"Frontiers in pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/36467025","citation_count":9,"is_preprint":false},{"pmid":"17651973","id":"PMC_17651973","title":"Identification of the infant-type R631C mutation in patients with the benign muscular form of CPT2 deficiency.","date":"2007","source":"Neuromuscular disorders : NMD","url":"https://pubmed.ncbi.nlm.nih.gov/17651973","citation_count":8,"is_preprint":false},{"pmid":"40246810","id":"PMC_40246810","title":"SLC25A42 promotes gastric cancer growth by conferring ferroptosis resistance through enhancing CPT2-mediated fatty acid oxidation.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/40246810","citation_count":7,"is_preprint":false},{"pmid":"27034144","id":"PMC_27034144","title":"Coexistence of VHL Disease and CPT2 Deficiency: A Case Report.","date":"2016","source":"Cancer research and treatment","url":"https://pubmed.ncbi.nlm.nih.gov/27034144","citation_count":7,"is_preprint":false},{"pmid":"40592838","id":"PMC_40592838","title":"SLC44A2 negatively regulates mitochondrial fatty acid oxidation to suppress colorectal progression by blocking the MUL1-CPT2 interaction.","date":"2025","source":"Cell death & disease","url":"https://pubmed.ncbi.nlm.nih.gov/40592838","citation_count":5,"is_preprint":false},{"pmid":"33857744","id":"PMC_33857744","title":"Loss of tumor suppressive properties of lipid metabolism enzyme CPT2 in ovarian carcinoma: Comment on \"CPT2 down-regulation promotes tumor growth and metastasis through inducing ROS/NFκB pathway in ovarian cancer\" by Zhang et al.","date":"2021","source":"Translational oncology","url":"https://pubmed.ncbi.nlm.nih.gov/33857744","citation_count":5,"is_preprint":false},{"pmid":"41107458","id":"PMC_41107458","title":"CPT2 inhibition enhances selective autophagy and proliferation in colorectal cancer via GPAT4-dependent glycerophospholipid biosynthesis.","date":"2025","source":"Communications biology","url":"https://pubmed.ncbi.nlm.nih.gov/41107458","citation_count":3,"is_preprint":false},{"pmid":"41074134","id":"PMC_41074134","title":"Porphyromonas gingivalis extracellular vesicles exacerbated osteoporosis by disrupting osteoblast mitochondrial dynamics and inhibiting Cpt2-regulated fatty acid oxidation.","date":"2025","source":"Journal of nanobiotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/41074134","citation_count":3,"is_preprint":false},{"pmid":"39429887","id":"PMC_39429887","title":"Recurrent rhabdomyolysis caused by palmitoyltransferase II (CPT-2) deficiency but complete normal acylcarnitine profile: A patient presentation and review of the literature.","date":"2024","source":"Molecular genetics and metabolism reports","url":"https://pubmed.ncbi.nlm.nih.gov/39429887","citation_count":3,"is_preprint":false},{"pmid":"40671144","id":"PMC_40671144","title":"SIRT3 mediates CPT2 delactylation to enhance mitochondrial function and proliferation in goat granulosa cells.","date":"2025","source":"Journal of animal science and biotechnology","url":"https://pubmed.ncbi.nlm.nih.gov/40671144","citation_count":2,"is_preprint":false},{"pmid":"37926998","id":"PMC_37926998","title":"SGMS1-AS1/MicroRNA-106a-5p/CPT2 Axis as a Novel Target for Regulating Lactate Metabolism in Colon Cancer.","date":"2023","source":"Technology in cancer research & treatment","url":"https://pubmed.ncbi.nlm.nih.gov/37926998","citation_count":2,"is_preprint":false},{"pmid":"27974123","id":"PMC_27974123","title":"[CPT2 gene mutation analysis and prenatal diagnosis in a family with carnitine palmitoyltransferase II deficiency].","date":"2016","source":"Zhongguo dang dai er ke za zhi = Chinese journal of contemporary pediatrics","url":"https://pubmed.ncbi.nlm.nih.gov/27974123","citation_count":2,"is_preprint":false},{"pmid":"36478999","id":"PMC_36478999","title":"A rare presentation of Carnitine palmitoyltransferase II (CPT-2) deficiency with normal acylcarnitine profile in a 10-year-old boy with muscle weakness and bilateral hearing loss; a case report.","date":"2022","source":"Iranian journal of child neurology","url":"https://pubmed.ncbi.nlm.nih.gov/36478999","citation_count":2,"is_preprint":false},{"pmid":"38798358","id":"PMC_38798358","title":"CPT2 mediated fatty acid oxidation is dispensable for humoral immunity.","date":"2024","source":"bioRxiv : the preprint server for biology","url":"https://pubmed.ncbi.nlm.nih.gov/38798358","citation_count":1,"is_preprint":false},{"pmid":"37020897","id":"PMC_37020897","title":"Dataset from dried blood spot acylcarnitine for detection of Carnitine-Acylcarnitine Translocase (CACT) deficiency and Carnitine Palmitoyl Transferase 2 (CPT2) deficiency.","date":"2023","source":"Data in brief","url":"https://pubmed.ncbi.nlm.nih.gov/37020897","citation_count":1,"is_preprint":false},{"pmid":"40386589","id":"PMC_40386589","title":"Downregulation of CPT2 promotes proliferation and migration through the TNFα/NF-κB pathway in cholangiocarcinoma.","date":"2025","source":"Journal of gastrointestinal oncology","url":"https://pubmed.ncbi.nlm.nih.gov/40386589","citation_count":0,"is_preprint":false},{"pmid":"35372350","id":"PMC_35372350","title":"Whole-Exome Sequencing Identifies a Novel CPT2 Mutation in a Pedigree With Gout.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/35372350","citation_count":0,"is_preprint":false},{"pmid":"38168614","id":"PMC_38168614","title":"Low C0 and normal C16 and C18:1 masking the diagnosis of carnitine palmitoyltransferase II deficiency including a novel CPT2 variant: A case report.","date":"2024","source":"Archives de pediatrie : organe officiel de la Societe francaise de pediatrie","url":"https://pubmed.ncbi.nlm.nih.gov/38168614","citation_count":0,"is_preprint":false},{"pmid":"39850164","id":"PMC_39850164","title":"Carnitine Palmitoyltransferase II (CPT2) Deficiency in a Patient With Recurrent Rhabdomyolysis: A Case Report.","date":"2024","source":"Cureus","url":"https://pubmed.ncbi.nlm.nih.gov/39850164","citation_count":0,"is_preprint":false},{"pmid":"41668040","id":"PMC_41668040","title":"SOX8/CPT2 axis regulates lipid metabolism to support enzalutamide resistance in prostate cancer.","date":"2026","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/41668040","citation_count":0,"is_preprint":false},{"pmid":"36060793","id":"PMC_36060793","title":"Corrigendum: Whole-exome sequencing identifies a novel CPT2 mutation in a pedigree with gout.","date":"2022","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/36060793","citation_count":0,"is_preprint":false},{"pmid":null,"id":"bio_10.1101_2025.11.04.686626","title":"Mitochondrial bioenergetic signatures differentiate asymptomatic from symptomatic Alzheimer’s disease","date":"2025-11-06","source":"bioRxiv","url":"https://doi.org/10.1101/2025.11.04.686626","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2024.10.08.616548","title":"Anti-tumor activity of camptothecin analog conjugate of a RSPO4-based peptibody targeting LGR4/5/6 in preclinical models of colorectal cancer","date":"2024-10-11","source":"bioRxiv","url":"https://doi.org/10.1101/2024.10.08.616548","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.04.25.650662","title":"RSPO2-based peptibodies conjugated with pyrrolobenzodiazepine dimer or camptothecin analogs demonstrate potent anti-tumor activity by targeting the three receptors LGR4/5/6 in colorectal cancer and neuroblastoma","date":"2025-04-29","source":"bioRxiv","url":"https://doi.org/10.1101/2025.04.25.650662","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.03.13.643011","title":"Spatial Transcriptomics and Single-Nucleus RNA Sequencing Reveal rAAV2- and rAAV9-Specific Transduction Signatures in the Mouse Liver","date":"2025-03-15","source":"bioRxiv","url":"https://doi.org/10.1101/2025.03.13.643011","citation_count":0,"is_preprint":true},{"pmid":null,"id":"bio_10.1101_2025.01.16.633354","title":"Metabolic shifts in the heart of hypothyroid mice — insights from untargeted metabolomics","date":"2025-01-20","source":"bioRxiv","url":"https://doi.org/10.1101/2025.01.16.633354","citation_count":0,"is_preprint":true}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":27099,"output_tokens":4519,"usd":0.074541,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12641,"output_tokens":5253,"usd":0.097265,"stage2_stop_reason":"end_turn"},"total_usd":0.171806,"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\": 1990,\n      \"finding\": \"CPT2 (carnitine palmitoyltransferase from inner mitochondrial membrane) is intrinsically insensitive to malonyl-CoA inhibition, but becomes inhibitable by malonyl-CoA when reconstituted with a malonyl-CoA-binding protein derived from the outer mitochondrial membrane, demonstrating that malonyl-CoA sensitivity requires the outer membrane component.\",\n      \"method\": \"Reconstitution experiment: cholate-extracted inner and outer mitochondrial membrane fractions combined in vitro; [14C]malonyl-CoA binding assay; CPT activity assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro reconstitution with defined fractions, single lab but rigorous biochemical dissection\",\n      \"pmids\": [\"2401367\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1989,\n      \"finding\": \"CPT2 activity in muscle is distinguishable from CPT1 activity by isotope exchange assay; patients with hepatic CPT1 deficiency (confirmed in fibroblasts) show normal CPT1 and CPT2 activities in muscle, whereas patients with muscular CPT2 deficiency show marked absolute deficiency (<12% residual) of CPT2 in muscle, supporting that CPT1 and CPT2 are separate proteins and that CPT1 may exist as tissue-specific isoforms.\",\n      \"method\": \"Isotope exchange assay differentiating CPT1 and CPT2 activities in muscle biopsies; kinetic analysis with varying carnitine and palmitoyl-CoA concentrations\",\n      \"journal\": \"Journal of the neurological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct enzymatic assay in patient tissues with kinetic dissection; single lab, multiple patient samples\",\n      \"pmids\": [\"2809620\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Missense mutations E174K and F383Y in CPT2 markedly decrease catalytic activity of the enzyme, as demonstrated by transfection of mutant constructs in COS-1 cells; a polymorphism F352C does not alter CPT2 activity. Genotype-phenotype correlations show homozygous F383Y causes hepatic phenotype and homozygous E174K causes muscular phenotype.\",\n      \"method\": \"Site-directed mutagenesis; transfection of mutant CPT2 cDNA in COS-1 cells; enzymatic activity assay\",\n      \"journal\": \"Human mutation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro mutagenesis with functional activity readout in transfected cells; single lab\",\n      \"pmids\": [\"9600456\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Low-level palmitate activates CDK1, which phosphorylates SIRT3; SIRT3 in turn deacetylates CPT2 and promotes CPT2 dimerization, enhancing fatty acid oxidation and mitochondrial homeostasis in liver cells.\",\n      \"method\": \"CDK1 kinase assay; SIRT3 deacetylase assay; co-immunoprecipitation; acetylation state analysis of CPT2; CPT2 dimerization assay; in vivo mouse model with CCl4 hepatotoxicity\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple biochemical assays (kinase, deacetylase, dimerization) in single lab; in vitro and in vivo validation\",\n      \"pmids\": [\"31866205\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"HRD1 (an E3 ubiquitin ligase) directly ubiquitinates CPT2 via K48-linked ubiquitination, stabilizing CPT2 protein and thereby supporting fatty acid oxidation in triple-negative breast cancer cells; HRD1 expression is downregulated under glutamine deprivation, reducing CPT2 stability.\",\n      \"method\": \"Co-immunoprecipitation; ubiquitination assay; K48-linkage-specific ubiquitin detection; CPT2 protein stability assays; knockdown/overexpression in TNBC cell lines in vitro and in vivo\",\n      \"journal\": \"Molecular oncology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and ubiquitination linkage assay; single lab, multiple orthogonal methods\",\n      \"pmids\": [\"33207079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"E2F2 binds directly to the Cpt2 promoter and transcriptionally represses CPT2 expression in the context of NAFLD-related hepatocarcinogenesis; E2f2 knockout in mice enhances fatty acid oxidation and increases CPT2 expression, while E2f2 overexpression elicits opposing effects.\",\n      \"method\": \"Chromatin immunoprecipitation (ChIP) showing E2F2 binding to Cpt2 promoter; E2f1-/- and E2f2-/- mouse models; E2f2 liver-specific knockdown and overexpression; FAO flux measurements\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — ChIP demonstrating direct promoter binding plus genetic KO and OE models; single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"33771899\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CPT2 acetylation at K79 (caused by NAD+ depletion and reduced SIRT3 activity) attenuates fatty acid oxidation and promotes accumulation of long-chain acylcarnitines, leading to mitochondrial damage and platelet storage lesion; SIRT3 agonists or antioxidants reverse this effect.\",\n      \"method\": \"Acetylation site identification; SIRT3 activity assays; fatty acid oxidation flux measurements; mitochondrial function assays; in vitro platelet storage and in vivo transfusion models\",\n      \"journal\": \"Blood advances\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific acetylation site identified with functional FAO readout and in vivo rescue; single lab\",\n      \"pmids\": [\"35728063\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"SIRT5, a lysine de-succinylase, de-succinylates CPT2 at Lys424; succinylation of K424 inactivates CPT2 enzymatic activity, impairing conversion of fatty acyl-carnitines to fatty acyl-CoA. Sirt5 deficiency increases K424 succinylation and causes accumulation of medium- and long-chain fatty acyl-carnitines. CPT2 K424R mutation (mimicking de-succinylation) rescues enzymatic activity and FAO impairment in Sirt5-KO hearts.\",\n      \"method\": \"Succinylomics proteomics; site-specific mutagenesis (K424R); CPT2 enzymatic activity assay; acylcarnitine metabolomics; Sirt5 KO and overexpression in diabetic mouse model; FAO flux measurement\",\n      \"journal\": \"Redox biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — succinylomics identification, mutagenesis validation, enzymatic activity assay, and in vivo rescue in multiple models; multiple orthogonal methods\",\n      \"pmids\": [\"38718533\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SIRT2, localized to cardiac mitochondria, deacetylates CPT2 at K239; this deacetylation promotes CPT2 ubiquitination, decreasing CPT2 protein stability and thereby inhibiting fatty acid oxidation and ROS production in the diabetic heart.\",\n      \"method\": \"Co-immunoprecipitation; deacetylation assay; K239 acetylation site identification; ubiquitination assay; CPT2 protein stability measurement; SIRT2 cardiac-specific overexpression/knockdown in STZ/HFD mouse model\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific acetylation site with functional stability readout and in vivo model; single lab, multiple methods\",\n      \"pmids\": [\"39781464\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"FAM3A promotes transcription of CPT2 through a signaling cascade: FAM3A-induced ATP release activates P2 receptors, promoting nuclear translocation of calmodulin (CaM), which acts as a co-activator of FOXA2 to drive CPT2 promoter activity and increase fatty acid oxidation.\",\n      \"method\": \"RNA sequencing; FOXA2 ChIP/promoter assay; CaM nuclear translocation imaging; CPT2 mRNA/protein measurement; FAM3A-deficient hepatocytes and mice; imipramine pharmacology\",\n      \"journal\": \"Metabolism: clinical and experimental\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pathway placed by epistasis (FAM3A KO abrogates CaM-FOXA2-CPT2 activation) with multiple orthogonal methods; single lab\",\n      \"pmids\": [\"35995281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Pharmacological inhibition of CPT2-dependent FAO (by aminocarnitine) in LPS-induced endotoxaemia causes accumulation of long-chain acylcarnitines, inhibits cardiac pyruvate metabolism, and exacerbates inflammation-induced cardiac dysfunction, demonstrating that CPT2 activity is required to prevent acylcarnitine-mediated mitochondrial dysfunction.\",\n      \"method\": \"Pharmacological CPT2 inhibition with aminocarnitine in vivo; cardiac mitochondrial respiration; acylcarnitine metabolite quantification; cardiac function measurement\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — specific inhibitor with mechanistic metabolite and functional readouts in vivo; single lab\",\n      \"pmids\": [\"32896106\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SIRT3 interacts with CPT2 and stabilizes the CPT2 protein by mediating de-lactylation of CPT2, prolonging its half-life and preventing its degradation; CPT2 overexpression enhances fatty acid β-oxidation and promotes granulosa cell proliferation via increased β-catenin and cyclin D1 levels.\",\n      \"method\": \"Co-immunoprecipitation (SIRT3-CPT2 interaction); CPT2 protein half-life measurement; lactylation/de-lactylation assay; CPT2 overexpression in goat granulosa cells; FAO and mitochondrial function assays\",\n      \"journal\": \"Journal of animal science and biotechnology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus PTM (lactylation) functional assay and half-life measurement; single lab, orthogonal methods\",\n      \"pmids\": [\"40671144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MUL1 (mitochondrial E3 ubiquitin ligase 1) promotes ubiquitin-mediated degradation of CPT2; SLC44A2 enhances the interaction between MUL1 and CPT2 (without increasing MUL1 expression), facilitating CPT2 degradation and inhibiting mitochondrial fatty acid oxidation.\",\n      \"method\": \"Co-immunoprecipitation (MUL1-CPT2 interaction); CPT2 protein stability/ubiquitination assays; SLC44A2 overexpression/knockdown; FAO flux measurements in CRC cells in vitro and in vivo\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP demonstrating protein interaction with ubiquitination and stability readout; single lab, multiple orthogonal approaches\",\n      \"pmids\": [\"40592838\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"SLC25A42 (mitochondrial CoA transporter) upregulates CPT2 acetylation and thereby increases CPT2 expression and activity, reprogramming lipid metabolism to enhance fatty acid oxidation-mediated mitochondrial respiration and reduce ferroptosis in gastric cancer cells.\",\n      \"method\": \"CPT2 acetylation analysis; co-immunoprecipitation; FAO flux (Seahorse); ROS and free fatty acid measurements; SLC25A42 KD/OE in vitro and in vivo\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — acetylation link to CPT2 reported but mechanistic detail thin in abstract; single lab, limited methodological detail\",\n      \"pmids\": [\"40246810\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"AMPK activation by GSK773 upregulates CPT2 protein expression in CPT2-deficient patient myotubes, correcting deficient FAO flux and acylcarnitine accumulation; effects are mediated through PGC-1α, ROS, and p38 MAPK pathways; AMPK is constitutively activated in CPT2-deficient myotubes.\",\n      \"method\": \"Patient-derived myotubes with CPT2 mutations; FAO flux assay; acylcarnitine profiling; CPT2 protein quantification; siRNA knockdowns; pharmacological inhibitors; mitochondrial biogenesis markers\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — human patient-derived cells with multiple metabolic and genetic perturbations; single lab\",\n      \"pmids\": [\"30007356\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CPT2-mediated long-chain fatty acid oxidation is dispensable for B cell development, activation, germinal center formation, and antibody production; stable 13C isotope tracing confirms CPT2 deficiency abolishes fatty acid-derived citrate production in B cells, yet humoral immunity is unaffected.\",\n      \"method\": \"Lymphocyte-specific CPT2 knockout mouse; stable [13C] isotope tracing of fatty acid-derived citrate; B cell developmental and functional assays (FACS, GC formation, Ab titers)\",\n      \"journal\": \"Journal of immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — genetic KO with isotope tracing and comprehensive immune phenotyping; negative mechanistic finding well-established\",\n      \"pmids\": [\"39258879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CPT2 R631C mutation leads to reduced fluorescence intensity compared to wild-type when expressed in cells (suggesting increased protein degradation), and reduces the ability of CPT2 to bind UCP2, without altering subcellular localization.\",\n      \"method\": \"Fluorescence intensity measurement of WT vs. mutant CPT2 in transfected cells; co-immunoprecipitation/interaction assay with UCP2; localization imaging\",\n      \"journal\": \"Frontiers in cell and developmental biology\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, limited mechanistic follow-up from WES study; interaction with UCP2 shown by single method\",\n      \"pmids\": [\"35372350\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CPT2 encodes the inner mitochondrial membrane enzyme carnitine palmitoyltransferase II, which converts fatty acyl-carnitines back to fatty acyl-CoA to enable mitochondrial β-oxidation; its activity is intrinsically malonyl-CoA-insensitive but can be regulated by the outer membrane malonyl-CoA-binding protein, and is controlled post-translationally by multiple sirtuins—SIRT5 de-succinylates K424 to activate it, SIRT3 deacetylates and dimerizes it (and de-lactylates it to stabilize it), and SIRT2 deacetylates K239 to promote its ubiquitination and degradation—while transcriptional repressors E2F1/E2F2 and a FAM3A-CaM-FOXA2 axis regulate its expression, and E3 ligases HRD1 (stabilizing K48-ubiquitination) and MUL1 (degradative ubiquitination, enhanced by SLC44A2) control its protein stability, together making CPT2 a nexus for fatty acid oxidation regulation in heart, liver, muscle, and immune cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CPT2 encodes the inner mitochondrial membrane carnitine palmitoyltransferase that reconverts fatty acyl-carnitines to fatty acyl-CoA, the committed step enabling mitochondrial long-chain fatty acid β-oxidation [#0, #7]. Unlike the outer-membrane CPT1, CPT2 is intrinsically insensitive to malonyl-CoA and acquires this sensitivity only when reconstituted with an outer-membrane malonyl-CoA-binding component, establishing it as a topologically and functionally distinct enzyme [#0, #1]. Catalytic activity depends on intact active-site architecture, as disease-associated missense substitutions (E174K, F383Y) sharply reduce activity and segregate with muscular versus hepatic clinical phenotypes, defining CPT2 as the gene underlying carnitine palmitoyltransferase II deficiency [#2, #14]. CPT2 is a major node for post-translational control of fatty acid oxidation through reversible lysine acylation: SIRT5 de-succinylates K424 to relieve succinylation-mediated inactivation [#7], SIRT3 deacetylates the enzyme to promote its catalytically active dimer [#3], and acetylation at K79 conversely suppresses oxidation and drives long-chain acylcarnitine accumulation [#6]. Protein abundance is set by competing ubiquitin ligases—HRD1 stabilizes CPT2 via K48-linked ubiquitination to sustain oxidation, while MUL1, aided by SLC44A2, drives its degradation, and SIRT2-mediated K239 deacetylation promotes its ubiquitin-dependent turnover [#4, #12, #8]. At the transcriptional level CPT2 is repressed by E2F2 and induced through a FAM3A–calmodulin–FOXA2 axis [#5, #9]. Functionally, loss of CPT2 activity causes accumulation of long-chain acylcarnitines and mitochondrial dysfunction across heart, liver, muscle, and platelets, whereas its activity is dispensable for B-cell development and humoral immunity [#10, #6, #15].\",\n  \"teleology\": [\n    {\n      \"year\": 1989,\n      \"claim\": \"Established that CPT2 is a protein biochemically and genetically separable from CPT1, resolving whether muscle and liver carnitine palmitoyltransferase deficiencies arise from distinct enzymes.\",\n      \"evidence\": \"Isotope exchange enzymatic assays distinguishing CPT1 and CPT2 activities in patient muscle biopsies and fibroblasts\",\n      \"pmids\": [\"2809620\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Did not define the molecular basis of the residual activity or the gene sequence\", \"Tissue-specific CPT1 isoform hypothesis not resolved at the protein level\"]\n    },\n    {\n      \"year\": 1990,\n      \"claim\": \"Defined the topological logic of malonyl-CoA regulation by showing CPT2 is intrinsically malonyl-CoA-insensitive and only acquires sensitivity from an outer-membrane binding partner.\",\n      \"evidence\": \"In vitro reconstitution of cholate-extracted inner and outer mitochondrial membrane fractions with malonyl-CoA binding and CPT activity assays\",\n      \"pmids\": [\"2401367\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular identity of the malonyl-CoA-binding outer-membrane component not defined here\", \"Stoichiometry and physical interaction with CPT2 not mapped\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Connected specific missense mutations to loss of catalytic activity and to genotype-phenotype correlation, establishing CPT2 as the causal gene for carnitine palmitoyltransferase II deficiency.\",\n      \"evidence\": \"Site-directed mutagenesis of CPT2 with expression and enzymatic activity assays in COS-1 cells\",\n      \"pmids\": [\"9600456\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural explanation of how E174K/F383Y impair catalysis\", \"Mechanism linking specific mutations to hepatic vs muscular tissue phenotype unresolved\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Showed that CPT2-deficient FAO can be pharmacologically corrected by raising CPT2 protein, opening a therapeutic route in patient cells.\",\n      \"evidence\": \"AMPK activator (GSK773) treatment of CPT2-mutant patient-derived myotubes with FAO flux, acylcarnitine profiling, and pathway perturbation\",\n      \"pmids\": [\"30007356\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether correction depends on mutant residual activity vs increased abundance not separated\", \"PGC-1α/ROS/p38 contributions defined only pharmacologically\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Identified deacetylation as an activating switch by showing a palmitate-CDK1-SIRT3 cascade deacetylates CPT2 and drives its active dimer.\",\n      \"evidence\": \"Kinase and deacetylase assays, co-IP, acetylation and dimerization analysis in liver cells plus a CCl4 mouse model\",\n      \"pmids\": [\"31866205\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific deacetylated lysines not mapped in this study\", \"Quantitative link between dimerization and catalytic rate not established\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Demonstrated that ubiquitination can stabilize rather than degrade CPT2, linking metabolic stress to CPT2 abundance via HRD1.\",\n      \"evidence\": \"Reciprocal co-IP, K48-linkage-specific ubiquitination and stability assays in TNBC cells in vitro and in vivo\",\n      \"pmids\": [\"33207079\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitinated lysine residues on CPT2 not mapped\", \"How K48 chains stabilize rather than target CPT2 mechanistically unexplained\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"Established physiologically that CPT2 flux is required to clear long-chain acylcarnitines and protect mitochondrial and cardiac function during inflammation.\",\n      \"evidence\": \"Pharmacological CPT2 inhibition (aminocarnitine) in LPS endotoxaemia with cardiac respiration, acylcarnitine, and function readouts\",\n      \"pmids\": [\"32896106\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Inhibitor specificity for CPT2 not orthogonally confirmed genetically\", \"Direct toxicity mechanism of accumulated acylcarnitines not dissected\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Placed CPT2 under direct transcriptional repression by E2F2 in the fatty-liver-to-cancer transition.\",\n      \"evidence\": \"ChIP showing E2F2 binding to the Cpt2 promoter with E2f2 knockout, knockdown, and overexpression mouse models and FAO flux\",\n      \"pmids\": [\"33771899\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"E2F1 contribution relative to E2F2 not fully separated\", \"Coregulators at the Cpt2 promoter not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined an inhibitory acetylation site (K79) whose accumulation under NAD+/SIRT3 decline causes acylcarnitine buildup and organelle damage.\",\n      \"evidence\": \"Acetylation site identification, SIRT3 activity and FAO flux assays in platelet storage and transfusion models\",\n      \"pmids\": [\"35728063\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether K79 acetylation alters catalysis directly vs via stability not resolved\", \"Acetyltransferase responsible for K79 not identified\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Mapped a transcriptional activation route to CPT2 through a FAM3A-ATP-P2 receptor-calmodulin-FOXA2 signaling axis.\",\n      \"evidence\": \"RNA-seq, FOXA2 ChIP/promoter assay, CaM nuclear translocation imaging in FAM3A-deficient hepatocytes and mice\",\n      \"pmids\": [\"35995281\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct FOXA2 binding to the CPT2 promoter vs indirect effect not fully distinguished\", \"Which P2 receptor subtype mediates the signal not pinned down\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Linked a CPT2 variant (R631C) to reduced protein abundance and loss of a UCP2 interaction without altered localization.\",\n      \"evidence\": \"Fluorescence intensity comparison of WT vs mutant CPT2, co-IP with UCP2, and localization imaging in transfected cells\",\n      \"pmids\": [\"35372350\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"UCP2 interaction shown by a single method without reciprocal or endogenous validation\", \"Functional consequence of lost UCP2 binding for FAO not measured\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identified succinylation at K424 as an inactivating modification reversed by SIRT5, establishing a desuccinylation-dependent activity switch validated by mutational rescue.\",\n      \"evidence\": \"Succinylomics, K424R mutagenesis, enzymatic activity and acylcarnitine metabolomics with Sirt5 KO/overexpression diabetic mouse models\",\n      \"pmids\": [\"38718533\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Succinyltransferase or non-enzymatic source of K424 succinylation not defined\", \"Structural basis for K424 succinylation-induced inactivation not solved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Showed CPT2-dependent long-chain FAO is dispensable for humoral immunity, delimiting where CPT2 function is metabolically required.\",\n      \"evidence\": \"Lymphocyte-specific CPT2 knockout mice with 13C isotope tracing and comprehensive B-cell developmental and functional assays\",\n      \"pmids\": [\"39258879\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other immune lineages depend on CPT2 not addressed\", \"Compensatory metabolic pathways in B cells not characterized\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Expanded the SIRT3-CPT2 relationship to a de-lactylation mechanism that stabilizes CPT2 and links FAO to granulosa cell proliferation.\",\n      \"evidence\": \"Co-IP, half-life measurement, lactylation/de-lactylation and FAO assays with CPT2 overexpression in goat granulosa cells\",\n      \"pmids\": [\"40671144\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Lactylated residues on CPT2 not mapped\", \"Causal link between CPT2 stabilization and β-catenin/cyclin D1 induction not mechanistically traced\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Defined SIRT2 as a deacetylase that destabilizes CPT2 by promoting K239-dependent ubiquitination, showing deacetylation can reduce rather than increase CPT2 function.\",\n      \"evidence\": \"Co-IP, K239 acetylation site identification, deacetylation and ubiquitination assays with cardiac-specific SIRT2 manipulation in diabetic mice\",\n      \"pmids\": [\"39781464\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Ubiquitin ligase coupling K239 deacetylation to degradation not identified\", \"Reconciliation with SIRT3 activating deacetylation at other residues not addressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Identified MUL1 as a degradative E3 ligase for CPT2 whose action is potentiated by SLC44A2, providing a mitochondrial route to suppress FAO.\",\n      \"evidence\": \"Co-IP, ubiquitination and stability assays with SLC44A2 manipulation and FAO flux in colorectal cancer cells in vitro and in vivo\",\n      \"pmids\": [\"40592838\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"MUL1-ubiquitinated lysines on CPT2 not mapped\", \"How SLC44A2 enhances the MUL1-CPT2 interaction structurally unknown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Linked the mitochondrial CoA transporter SLC25A42 to increased CPT2 acetylation, expression and FAO with reduced ferroptosis in gastric cancer.\",\n      \"evidence\": \"CPT2 acetylation analysis, co-IP, Seahorse FAO flux, and ROS/free fatty acid measurements with SLC25A42 KD/OE\",\n      \"pmids\": [\"40246810\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Mechanistic detail of how acetylation increases CPT2 activity here is thin and not site-resolved\", \"Apparent activation by acetylation conflicts with inactivating acetylation reports and is unreconciled\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved how the competing acylation marks (succinylation, acetylation at distinct lysines, lactylation) and opposing ubiquitin ligases are integrated to set net CPT2 activity and abundance in a given tissue.\",\n      \"evidence\": \"No single study in the corpus reconciles the divergent PTM and stability mechanisms\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified structural model of how lysine modifications at K79, K239, K424 jointly control catalysis and turnover\", \"Cross-talk between HRD1 stabilization and MUL1/SIRT2 degradation not mapped\", \"Identity of the malonyl-CoA-binding outer-membrane partner from the original reconstitution remains undefined in the corpus\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 2, 7]},\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 7]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005739\", \"supporting_discovery_ids\": [0, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 7, 10, 15]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"SIRT3\",\n      \"SIRT5\",\n      \"SIRT2\",\n      \"HRD1\",\n      \"MUL1\",\n      \"SLC44A2\",\n      \"UCP2\"\n    ],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}