SLC25A4 (ANT1/AAC1) is the heart- and skeletal-muscle isoform of the mitochondrial ADP/ATP carrier (adenine nucleotide translocase), a member of the SLC25 mitochondrial carrier family. It is a multi-pass integral protein of the mitochondrial inner membrane that catalyzes the electrogenic 1:1 antiport of matrix ATP for cytosolic ADP, thereby exporting the ATP generated by oxidative phosphorylation to fuel the cell and importing ADP for re-phosphorylation by ATP synthase. It functions as a monomer with a single central substrate binding site that is alternately exposed to the cytosolic (c-state) and matrix (m-state) side of the membrane, and it operates by a ping-pong (double-displacement) kinetic mechanism. Substrate specificity is narrow, with ADP and ATP as the only physiological substrates. Beyond its core antiporter activity, ANT1 has been implicated as a component or regulator of the mitochondrial permeability transition pore (mPTP) and in mitochondrial proton leak/uncoupling, giving it secondary roles in regulated cell death and thermogenesis. In humans, dominant SLC25A4 mutations cause autosomal dominant progressive external ophthalmoplegia with multiple mtDNA deletions (PEOA2) and a severe early-onset mitochondrial disease with mtDNA depletion, while recessive loss-of-function causes mitochondrial myopathy and hypertrophic cardiomyopathy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005471 ATP:ADP antiporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: Phylogenetic (IBA) assertion of the core molecular function: ADP/ATP antiport across the mitochondrial inner membrane. This is the defining, experimentally established activity of ANT1 and is corroborated by direct transport assays (PMID:21586654, PMID:37278158, PMID:23173940). Supporting Evidence: PMID:37278158 The mitochondrial ADP/ATP carrier (SLC25A4), also called the adenine nucleotide translocase, imports ADP into the mitochondrial matrix and exports ATP, which are key steps in oxidative phosphorylation. |
| GO:0005743 mitochondrial inner membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Correct site of action. ANT1 is a multi-pass inner mitochondrial membrane protein where the ADP/ATP exchange occurs; supported directly by PMID:21586654 and by UniProt subcellular location. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane |
| GO:0005757 mitochondrial permeability transition pore complex | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: ANT1 is a long-proposed regulator/component of the mitochondrial permeability transition pore (mPTP). This is a genuine secondary role, but UniProt notes it remains unclear whether ANT1 is a pore-forming component or a regulator, so this is not the core function. Retained as a non-core annotation. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt It is however unclear if SLC25A4/ANT1 constitutes a pore-forming component of mPTP or regulates it |
| GO:0046902 regulation of mitochondrial membrane permeability | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Reflects the mPTP-related role of ANT1 in controlling inner-membrane permeability during permeability transition. A real but secondary (non-core) role relative to its ADP/ATP antiporter function. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt Also plays a key role in mPTP opening, a non-specific pore that enables free passage of the mitochondrial membranes to solutes of up to 1.5 kDa, and which contributes to cell death |
| GO:1990544 mitochondrial ATP transmembrane transport | IBA GO_REF:0000033 | ACCEPT | Summary: Correct core biological process: export of ATP across the mitochondrial inner membrane. This is one half of the ADP/ATP exchange reaction and is directly supported experimentally (PMID:21586654). Supporting Evidence: PMID:37278158 imports ADP into the mitochondrial matrix and exports ATP, which are key steps in oxidative phosphorylation |
| GO:0005471 ATP:ADP antiporter activity | IEA GO_REF:0000120 | ACCEPT | Summary: Electronic assertion of the core molecular function, consistent with the experimental evidence. Correct. |
| GO:0005739 mitochondrion | IEA GO_REF:0000117 | KEEP AS NON CORE | Summary: Correct but non-specific localization. The more precise inner-membrane term is separately annotated and better represents the site of action. |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Correct localization to the mitochondrial inner membrane, consistent with experimental evidence (PMID:21586654) and UniProt. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane |
| GO:0015853 adenine transport | IEA GO_REF:0000108 | REMOVE | Summary: This term is derived by inter-ontology inference from an old, overly broad "adenine transmembrane transporter activity" assertion (see the PMID:2823266 TAS annotation). ANT1 transports the adenine nucleotides ADP and ATP, not free adenine base; its substrate specificity is narrow (only ADP and ATP; PMID:23173940). Free-adenine transport is a mischaracterization of the carrier and should be removed as an incorrect electronic inference. Supporting Evidence: PMID:23173940 A large number of nucleotides were tested, but only ADP and ATP are suitable substrates for human AAC1, demonstrating a very narrow specificity. |
| GO:0016020 membrane | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Uninformatively general localization subsumed by the specific mitochondrial-inner-membrane annotation. Kept as non-core rather than treated as core. |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | KEEP AS NON CORE | Summary: Correct but very general parent process. More specific ADP/ATP-transmembrane-transport terms are annotated and better represent the function. |
| GO:0140021 mitochondrial ADP transmembrane transport | IEA GO_REF:0000120 | ACCEPT | Summary: Correct core biological process: import of ADP across the mitochondrial inner membrane, the counter-transport half of the exchange. Supported by direct assays (PMID:21586654, PMID:37278158). Supporting Evidence: PMID:37278158 imports ADP into the mitochondrial matrix and exports ATP, which are key steps in oxidative phosphorylation |
| GO:1902600 proton transmembrane transport | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Reflects the fatty-acid-dependent proton-leak/uncoupling activity of ANT that contributes to mitochondrial thermogenesis. This is a genuine but secondary role in humans (largely By similarity in UniProt), not the core antiporter function. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt Plays a role in mitochondrial uncoupling by acting as a proton transporter: proton transport uncouples the proton flows via the electron transport chain and ATP synthase |
| GO:1990544 mitochondrial ATP transmembrane transport | IEA GO_REF:0000120 | ACCEPT | Summary: Duplicate (electronic) of the core ATP-export process also asserted by IBA and IDA. Correct. |
| GO:0005515 protein binding | IPI PMID:21370995 Expression of leucine-rich repeat kinase 2 (LRRK2) inhibits ... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" (IPI with LRRK2). Uninformative as a molecular function; the specific interaction is captured better elsewhere. Marked as over-annotated per policy (experimental IPI is not removed). |
| GO:0005515 protein binding | IPI PMID:24316735 Orphan nuclear receptor TR3 acts in autophagic cell death vi... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" (IPI with NR4A1/TR3). Uninformative MF term; marked as over-annotated per policy. |
| GO:0005515 protein binding | IPI PMID:24725412 Ribosomal protein s15 phosphorylation mediates LRRK2 neurode... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" (IPI with LRRK2). Uninformative MF term; marked as over-annotated per policy. |
| GO:0005515 protein binding | IPI PMID:33961781 Dual proteome-scale networks reveal cell-specific remodeling... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" (IPI with the paralog SLC25A6/ANT3). High-throughput interactome mapping; uninformative MF term. Marked as over-annotated per policy. |
| GO:0005515 protein binding | IPI PMID:40355756 The solute carrier superfamily interactome. | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" (IPI with SLC25A6) from a solute-carrier interactome study. Uninformative MF term; marked as over-annotated per policy. |
| GO:0005757 mitochondrial permeability transition pore complex | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Electronic (Ensembl orthology) duplicate of the mPTP-component annotation. Genuine secondary role; retained as non-core. |
| GO:0015078 proton transmembrane transporter activity | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Reflects the secondary fatty-acid-activated proton-transport (uncoupling) activity of ANT. A real but non-core molecular function relative to ADP/ATP antiport; note this activity is inhibited by antiporter activity. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt Plays a role in mitochondrial uncoupling by acting as a proton transporter: proton transport uncouples the proton flows via the electron transport chain and ATP synthase to reduce the efficiency of ATP production and cause mitochondrial thermogenesis |
| GO:0017077 oxidative phosphorylation uncoupler activity | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Uncoupler activity via fatty-acid-dependent proton leak. Genuine secondary function contributing to thermogenesis, not the core antiporter function. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt proton transport uncouples the proton flows via the electron transport chain and ATP synthase to reduce the efficiency of ATP production and cause mitochondrial thermogenesis |
| GO:0046902 regulation of mitochondrial membrane permeability | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Electronic (Ensembl orthology) duplicate of the mPTP-related permeability regulation role. Genuine secondary role; retained as non-core. |
| GO:1901526 positive regulation of mitophagy | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: ANT1 promotes mitophagy independently of its transport activity, via interaction with TIMM44 leading to PINK1 stabilization. This is a By-similarity secondary role in UniProt; genuine but non-core. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt Acts as a regulator of mitophagy independently of ADP:ATP antiporter activity: promotes mitophagy via interaction with TIMM44, leading to inhibit the presequence translocase TIMM23, thereby promoting stabilization of PINK1 |
| GO:1990845 adaptive thermogenesis | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Reflects the uncoupling/proton-leak contribution of ANT to mitochondrial thermogenesis. Genuine but secondary; retained as non-core. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt proton transport uncouples the proton flows via the electron transport chain and ATP synthase to reduce the efficiency of ATP production and cause mitochondrial thermogenesis |
| GO:1990845 adaptive thermogenesis | TAS Reactome:R-HSA-166187 | KEEP AS NON CORE | Summary: Reactome-curated (Mitochondrial Uncoupling) assertion of the thermogenic role of ANT via proton leak. Consistent with UniProt; secondary/non-core relative to ADP/ATP antiport. |
| GO:0005739 mitochondrion | IDA GO_REF:0000052 | KEEP AS NON CORE | Summary: Direct (HPA immunofluorescence) evidence for mitochondrial localization. Correct but non-specific; the inner-membrane term is the informative one. |
| GO:0005471 ATP:ADP antiporter activity | EXP PMID:23173940 The substrate specificity of the human ADP/ATP carrier AAC1. | ACCEPT | Summary: Experimental determination of substrate specificity of human AAC1/ANT1 confirming it is a dedicated ADP/ATP antiporter with narrow specificity. Strong support for the core molecular function. Supporting Evidence: PMID:23173940 A large number of nucleotides were tested, but only ADP and ATP are suitable substrates for human AAC1, demonstrating a very narrow specificity. |
| GO:0005471 ATP:ADP antiporter activity | IDA PMID:37278158 Human mitochondrial ADP/ATP carrier SLC25A4 operates with a ... | ACCEPT | Summary: Direct kinetic characterization of purified, reconstituted human SLC25A4 demonstrating ADP/ATP exchange operating by a ping-pong mechanism. Strong direct support for the core molecular function. Supporting Evidence: PMID:37278158 The mitochondrial ADP/ATP carrier (SLC25A4), also called the adenine nucleotide translocase, imports ADP into the mitochondrial matrix and exports ATP |
| GO:0015217 ADP transmembrane transporter activity | IDA PMID:30046662 Expanding the phenotype of de novo SLC25A4-linked mitochondr... | ACCEPT | Summary: Direct assay of ADP/ATP transport by recombinant ANT1 (wild-type vs pathogenic p.Lys33Gln) in fused membrane vesicles. Represents one half of the antiport activity; a correct and more specific transporter-activity term for ANT1. Supporting Evidence: PMID:30046662 To determine the effect of a putative pathogenic p.Lys33Gln variant on ADP/ATP transport, the mutant protein was expressed in Lactococcus lactis and its transport activity was assessed with fused membrane vesicles. |
| GO:0015866 ADP transport | IDA PMID:30046662 Expanding the phenotype of de novo SLC25A4-linked mitochondr... | ACCEPT | Summary: Direct evidence for ADP transport activity of ANT1, with the pathogenic variant abolishing it. Correct BP; the mitochondrial-ADP-transmembrane child term is the more precise annotation. Supporting Evidence: PMID:30046662 significantly impaired ADP/ATP transport in Lactococcus lactis |
| GO:0140021 mitochondrial ADP transmembrane transport | IDA PMID:37278158 Human mitochondrial ADP/ATP carrier SLC25A4 operates with a ... | ACCEPT | Summary: Direct evidence for ADP import across the inner membrane from reconstituted-carrier transport assays. Core biological process. Supporting Evidence: PMID:37278158 imports ADP into the mitochondrial matrix and exports ATP, which are key steps in oxidative phosphorylation |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | KEEP AS NON CORE | Summary: High-throughput mitochondrial-proteome evidence for mitochondrial localization. Correct but non-specific. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-180905 | ACCEPT | Summary: Reactome-curated inner-membrane localization (in the context of HIV-1 Vpr association). Correct site of action. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-5250209 | ACCEPT | Summary: Reactome-curated inner-membrane localization (ARL2:GTP:ARL2BP binding SLC25A4). Correct site of action. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-5672027 | ACCEPT | Summary: Reactome-curated inner-membrane localization for the ATP/ADP exchange reaction. Correct site of action. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-9864415 | ACCEPT | Summary: Reactome-curated inner-membrane localization (proton import reaction). Correct site of action. |
| GO:0015078 proton transmembrane transporter activity | TAS Reactome:R-HSA-9864415 | KEEP AS NON CORE | Summary: Reactome-curated proton-transport activity ("AAC1 imports a proton"), corresponding to the secondary uncoupling/proton-leak function of ANT. A genuine but non-core molecular function. |
| GO:0005471 ATP:ADP antiporter activity | IDA PMID:21586654 adPEO mutations in ANT1 impair ADP-ATP translocation in musc... | ACCEPT | Summary: Direct measurement of ADP-ATP exchange function in disease-relevant mammalian muscle cells (myotubes), including pathogenic adPEO mutants. Strong direct support for the core molecular function. Supporting Evidence: PMID:21586654 mutant human ANT1 causes dominant mitochondrial defects characterized by decreased ADP-ATP exchange function and abnormal translocator reversal potential |
| GO:0005515 protein binding | IPI PMID:31883789 Human-Specific ARHGAP11B Acts in Mitochondria to Expand Neoc... | MARK AS OVER ANNOTATED | Summary: IPI capturing the interaction with the human-specific protein ARHGAP11B, which inhibits the mPTP. The specific interaction is biologically meaningful, but the bare "protein binding" term is uninformative; marked as over-annotated per policy (experimental IPI is not removed). Supporting Evidence: PMID:31883789 ARHGAP11B is imported into mitochondria, where it interacts with the adenine nucleotide translocase (ANT) and inhibits the mitochondrial permeability transition pore (mPTP). |
| GO:0005743 mitochondrial inner membrane | IDA PMID:21586654 adPEO mutations in ANT1 impair ADP-ATP translocation in musc... | ACCEPT | Summary: Direct evidence for inner-membrane localization from functional characterization in mammalian muscle mitochondria. Correct site of action. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt SUBCELLULAR LOCATION: Mitochondrion inner membrane |
| GO:0005757 mitochondrial permeability transition pore complex | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity transfer of the mPTP-component annotation. Genuine but non-core secondary role (component/regulator status of ANT in mPTP remains debated). |
| GO:0017077 oxidative phosphorylation uncoupler activity | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity transfer of the uncoupler (proton-leak) activity. Genuine secondary molecular function; non-core. |
| GO:0046902 regulation of mitochondrial membrane permeability | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity transfer of the mPTP-related permeability regulation role. Genuine but non-core. |
| GO:0140021 mitochondrial ADP transmembrane transport | IDA PMID:21586654 adPEO mutations in ANT1 impair ADP-ATP translocation in musc... | ACCEPT | Summary: Direct evidence for ADP import across the inner membrane (ADP-ATP exchange in muscle mitochondria). Core biological process. Supporting Evidence: PMID:21586654 decreased ADP-ATP exchange function and abnormal translocator reversal potential |
| GO:1901526 positive regulation of mitophagy | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity transfer of the transport-independent mitophagy role (via TIMM44/PINK1). Genuine but non-core. |
| GO:1990544 mitochondrial ATP transmembrane transport | IDA PMID:21586654 adPEO mutations in ANT1 impair ADP-ATP translocation in musc... | ACCEPT | Summary: Direct evidence for ATP export across the inner membrane (ADP-ATP exchange in muscle mitochondria). Core biological process. Supporting Evidence: PMID:21586654 decreased ADP-ATP exchange function and abnormal translocator reversal potential |
| GO:1990845 adaptive thermogenesis | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity transfer of the thermogenic (uncoupling) role. Genuine but non-core. |
| GO:0016020 membrane | IDA PMID:27641616 TSPO ligands stimulate ZnPPIX transport and ROS accumulation... | KEEP AS NON CORE | Summary: Direct evidence (TSPO-ligand/erythrocyte study) for membrane localization, including a possible non-mitochondrial membrane pool. Retained as non-core: "membrane" is uninformatively general and the primary functional location is the mitochondrial inner membrane. Supporting Evidence: file:human/SLC25A4/SLC25A4-uniprot.txt May localize to non-mitochondrial membranes (PubMed:27641616) |
| GO:0031966 mitochondrial membrane | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Sequence-similarity localization to mitochondrial membrane. Correct but less specific than the inner-membrane annotation. |
| GO:0015866 ADP transport | IMP PMID:27693233 Recurrent De Novo Dominant Mutations in SLC25A4 Cause Severe... | ACCEPT | Summary: Mutant-phenotype evidence: recombinant AAC1 disease mutants are severely impaired in ADP/ATP transport, supporting ANT1's role in ADP transport. Correct core biological process. Supporting Evidence: PMID:27693233 We show that both recombinant AAC1 mutant proteins are severely impaired in ADP/ATP transport |
| GO:0060546 negative regulation of necroptotic process | IMP PMID:16507998 Inhibition of ADP/ATP exchange in receptor-interacting prote... | KEEP AS NON CORE | Summary: Experimental (IMP) evidence that ANT-conducted ADP transport counteracts RIP-mediated necrotic cell death: TNF-alpha triggers RIP-dependent inhibition of ANT transport leading to ATP depletion and necrosis, and ectopic ANT expression prevents cell death. A genuine secondary role in regulated cell death; retained as non-core. Supporting Evidence: PMID:16507998 tumor necrosis factor alpha induced RIP-dependent inhibition of adenine nucleotide translocase (ANT)-conducted transport of ADP into mitochondria, which resulted in reduced ATP and necrotic cell death |
| GO:0005739 mitochondrion | HDA PMID:20833797 Phosphoproteome analysis of functional mitochondria isolated... | KEEP AS NON CORE | Summary: High-throughput (phosphoproteome of isolated muscle mitochondria) evidence for mitochondrial localization. Correct but non-specific. |
| GO:0005515 protein binding | IPI PMID:16507998 Inhibition of ADP/ATP exchange in receptor-interacting prote... | MARK AS OVER ANNOTATED | Summary: IPI capturing the ANT-cyclophilin D interaction relevant to mPTP/necrosis. Bare "protein binding" is uninformative as an MF; marked as over-annotated per policy (experimental IPI is not removed). Supporting Evidence: PMID:16507998 The inhibition of ADP/ATP exchange coincided with the loss of interaction between ANT and cyclophilin D |
| GO:0005739 mitochondrion | TAS PMID:10926541 Role of adenine nucleotide translocator 1 in mtDNA maintenan... | KEEP AS NON CORE | Summary: Author-stated (TAS) mitochondrial localization. Correct but non-specific. |
| GO:0005886 plasma membrane | TAS PMID:2823266 cDNA sequence of a human skeletal muscle ADP/ATP translocato... | UNDECIDED | Summary: Legacy TAS annotation from the 1987 cDNA-cloning paper. ANT1 is an inner mitochondrial membrane carrier; there is no credible evidence for a plasma-membrane function, and this TAS predates modern localization data. A minor non-mitochondrial membrane pool has been reported (PMID:27641616) but not a bona fide plasma-membrane role. This is a legacy mislocalization; UNDECIDED as it cannot be firmly refuted from the cached abstract, but it should not be treated as core. |
| GO:0006091 generation of precursor metabolites and energy | TAS PMID:2823266 cDNA sequence of a human skeletal muscle ADP/ATP translocato... | KEEP AS NON CORE | Summary: Correct but very general BP: ANT1 supplies ADP for and exports the ATP of oxidative phosphorylation. Subsumed by the specific ADP/ATP transport and OXPHOS-supporting annotations; retained as non-core. |
| GO:0015207 adenine transmembrane transporter activity | TAS PMID:2823266 cDNA sequence of a human skeletal muscle ADP/ATP translocato... | MODIFY | Summary: Legacy TAS from the 1987 cloning paper mislabels the carrier as an "adenine (base) transporter". ANT1 transports the adenine nucleotides ADP and ATP, not free adenine, and has narrow specificity (PMID:23173940). This is the source of the erroneous "adenine transport" inference; the correct MF is ATP:ADP antiporter activity. Modify to the accurate transporter term. Proposed replacements: ATP:ADP antiporter activity Supporting Evidence: PMID:23173940 A large number of nucleotides were tested, but only ADP and ATP are suitable substrates for human AAC1, demonstrating a very narrow specificity. |
Loading supporting content…
Download this section (compressed HTML)Q: Does human ANT1 constitute a pore-forming component of the mPTP, or does it act purely as a regulator of the pore?
Q: What is the physiological magnitude and regulation of ANT1-mediated fatty-acid-dependent proton leak in human heart/skeletal muscle, and how much does it contribute to adaptive thermogenesis in vivo?
Experiment: Reconstitute purified human ANT1 with defined mPTP components to test directly whether it is required for pore formation versus modulation.
Experiment: Quantify fatty-acid-activated proton conductance of reconstituted human ANT1 versus its ADP/ATP antiport activity to define the balance between energy output and thermogenesis.
Loading supporting content…
Download this section (compressed HTML)Loading supporting content…
Download this section (compressed HTML)