SLC25A5 (ADP/ATP translocase 2; ANT2; AAC2) is an ADP/ATP translocase (adenine nucleotide translocator) of the SLC25 mitochondrial carrier family. It is a polytopic integral protein of the mitochondrial inner membrane, built from three homologous Solcar repeats forming a six-transmembrane-helix carrier fold, and functions as an antiporter that exchanges ATP synthesized in the mitochondrial matrix for cytosolic ADP by an alternating-access (cytoplasmic-open/matrix-open) mechanism. This ATP:ADP exchange supplies the ATP-synthase/electron-transport chain with ADP and delivers ATP to the cytosol, making the carrier a central node of cellular energy homeostasis and oxidative phosphorylation. ANT2 is the isoform characteristically expressed in proliferative and glycolytic tissues (fibroblasts, growth-activated and undifferentiated cells, and many tumors). Beyond its antiporter activity, ANT can act as a fatty-acid-dependent proton transporter that uncouples oxidative phosphorylation and contributes to thermogenesis in tissues lacking UCP1, and it participates in mitochondrial permeability transition pore (mPTP) activity linked to apoptosis; it has also been reported as a component of the mitotic spindle-associated MMXD (MMS19-MIP18-XPD) cytosolic iron-sulfur assembly complex and as a regulator of PINK1-dependent mitophagy.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005471 ATP:ADP antiporter activity | IBA GO_REF:0000033 | ACCEPT | Summary: Core molecular function of ANT2: an inner-membrane antiporter that exchanges matrix ATP for cytosolic ADP. Strongly supported across the SLC25A4/5/6 orthologue set and by UniProt. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt mitochondrial matrix for ATP synthesis, and export of ATP out to fuel |
| GO:0005743 mitochondrial inner membrane | IBA GO_REF:0000033 | ACCEPT | Summary: Correct core location. ANT2 is a multi-pass protein of the mitochondrial inner membrane where its antiport activity occurs. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt Mitochondrion inner membrane |
| GO:0005757 mitochondrial permeability transition pore complex | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: ANT is associated with the mPTP, but whether it is a pore-forming component or a regulator is explicitly unresolved. A genuine but secondary/context-specific role, not the core transport function. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt SLC25A5/ANT2 constitutes a pore-forming component of mPTP or regulates |
| GO:0046902 regulation of mitochondrial membrane permeability | IBA GO_REF:0000033 | KEEP AS NON CORE | Summary: Consistent with ANT's role in mPTP/permeability transition. Secondary to the antiporter function; retained as non-core. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt Also plays a key role in mPTP |
| GO:1990544 mitochondrial ATP transmembrane transport | IBA GO_REF:0000033 | ACCEPT | Summary: Core biological process: export of matrix ATP is one half of the ADP/ATP antiport cycle. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt mitochondrial matrix for ATP synthesis, and export of ATP out to fuel |
| GO:0005471 ATP:ADP antiporter activity | IEA GO_REF:0000120 | ACCEPT | Summary: Duplicate of the IBA core-MF annotation via automated IEA pipelines; correct. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt Reaction=ADP(in) + ATP(out) = ADP(out) + ATP(in) |
| GO:0005739 mitochondrion | IEA GO_REF:0000117 | ACCEPT | Summary: Correct high-level compartment (parent of mitochondrial inner membrane). Accurate but less informative than GO:0005743. |
| GO:0005743 mitochondrial inner membrane | IEA GO_REF:0000120 | ACCEPT | Summary: Correct core location via automated pipeline; consistent with the IBA/ISS/TAS annotations to the same term. |
| GO:0015853 adenine transport | IEA GO_REF:0000108 | MODIFY | Summary: Incorrect substrate. This is an inter-ontology inference from the equally incorrect GO:0015207 (adenine transmembrane transporter activity). ANT transports the adenine nucleotides ADP and ATP, not free adenine (the base). The correct process is mitochondrial ADP/ATP transmembrane transport. Proposed replacements: mitochondrial ADP transmembrane transport |
| GO:0016020 membrane | IEA GO_REF:0000120 | MARK AS OVER ANNOTATED | Summary: Uninformative high-level parent of the specific mitochondrial inner membrane location. Not wrong, but over-general. |
| GO:0055085 transmembrane transport | IEA GO_REF:0000002 | MARK AS OVER ANNOTATED | Summary: Correct but high-level parent process; the specific mitochondrial ADP/ATP transport terms are preferred. |
| GO:0140021 mitochondrial ADP transmembrane transport | IEA GO_REF:0000120 | ACCEPT | Summary: Core biological process: import of cytosolic ADP into the matrix, the other half of the antiport cycle. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt ADP:ATP antiporter that mediates import of ADP into the |
| GO:1902600 proton transmembrane transport | IEA GO_REF:0000120 | KEEP AS NON CORE | Summary: Reflects ANT's secondary fatty-acid-dependent proton-transport/uncoupling activity, inferred electronically from GO:0015078/GO:0017077. Plausible but By-similarity only; retained as non-core. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt proton transporter: proton transport uncouples the proton flows via the |
| GO:1990544 mitochondrial ATP transmembrane transport | IEA GO_REF:0000120 | ACCEPT | Summary: Duplicate of the core ATP-export process annotation via IEA. Correct. |
| GO:0005515 protein binding | IPI PMID:17715127 Regulation of insulin secretion by SIRT4, a mitochondrial AD... | MARK AS OVER ANNOTATED | Summary: IntAct co-occurrence with SIRT4 (Q9Y6E7) from a mitochondrial ADP-ribosyltransferase study. Bare "protein binding" is uninformative about ANT2's molecular function. |
| GO:0005515 protein binding | IPI PMID:19154410 Identification of C2orf18, termed ANT2BP (ANT2-binding prote... | MARK AS OVER ANNOTATED | Summary: Interaction with ANT2BP/C2orf18/SLC35F6 (Q8N357), an ANT2-binding protein in pancreatic cancer. Real interaction but bare "protein binding" is uninformative as an MF; the functional consequence is captured by the proliferation/apoptosis BP annotations from the same paper. Supporting Evidence: PMID:19154410 it could interact with adenine nucleotide translocase 2 (ANT2) |
| GO:0005515 protein binding | IPI PMID:21370995 Expression of leucine-rich repeat kinase 2 (LRRK2) inhibits ... | MARK AS OVER ANNOTATED | Summary: IntAct interaction with LRRK2 (Q5S007) from an LRRK2/uMtCK study. Uninformative bare "protein binding". |
| GO:0005515 protein binding | IPI PMID:24725412 Ribosomal protein s15 phosphorylation mediates LRRK2 neurode... | MARK AS OVER ANNOTATED | Summary: IntAct interaction with LRRK2 (Q5S007) from an LRRK2 neurodegeneration study. Uninformative bare "protein binding". |
| GO:0005515 protein binding | IPI PMID:27499296 Mitochondrial Protein Interaction Mapping Identifies Regulat... | MARK AS OVER ANNOTATED | Summary: IntAct interaction with ADCK2 (Q7Z695) from a mitochondrial protein interaction map. Uninformative bare "protein binding". |
| GO:0005515 protein binding | IPI PMID:35266954 The E3 ligase TRIM1 ubiquitinates LRRK2 and controls its loc... | MARK AS OVER ANNOTATED | Summary: IntAct interaction with LRRK2 (Q5S007) from a TRIM1/LRRK2 study. Uninformative bare "protein binding". |
| GO:0005757 mitochondrial permeability transition pore complex | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: mPTP-complex membership transferred electronically from the mouse orthologue. Same secondary, unresolved (component vs regulator) role as the IBA/ISS mPTP annotations; non-core. |
| GO:0015078 proton transmembrane transporter activity | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: ANT's secondary uncoupling proton-transport activity, transferred from the paralog. Real but By-similarity; secondary to the antiporter MF. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt Plays a role in mitochondrial uncoupling by acting as a |
| GO:0017077 oxidative phosphorylation uncoupler activity | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Uncoupler activity via fatty-acid-dependent proton transport, transferred from the paralog. Secondary function; retained as non-core. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt cause mitochondrial thermogenesis |
| GO:0030183 B cell differentiation | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Transferred electronically from the mouse orthologue. Reflects the strong expression/role of ANT in proliferating lymphoid cells rather than a direct, human-ANT2-specific molecular contribution; non-core pleiotropy. |
| GO:0030218 erythrocyte differentiation | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Transferred from the mouse orthologue. ANT2 is detected in erythroid cells and the RBC membrane, but this is a physiological/context role, not the core transport function; non-core. |
| GO:0046902 regulation of mitochondrial membrane permeability | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Electronic duplicate of the mPTP/permeability regulation role. Non-core. |
| GO:1901526 positive regulation of mitophagy | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: ANT regulates PINK1-dependent mitophagy independently of antiport activity, via TIMM44/TIMM23; transferred from the paralog. Genuine but secondary; non-core. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt promotes mitophagy via interaction with |
| GO:1990845 adaptive thermogenesis | IEA GO_REF:0000107 | KEEP AS NON CORE | Summary: Downstream of the uncoupling proton-transport activity, transferred from the paralog. Secondary function; retained as non-core. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt cause mitochondrial thermogenesis |
| GO:0005739 mitochondrion | IDA GO_REF:0000052 | ACCEPT | Summary: Immunofluorescence (HPA) localization to mitochondria. Correct; a valid but high-level parent of the inner-membrane location. |
| GO:0005739 mitochondrion | HTP PMID:34800366 Quantitative high-confidence human mitochondrial proteome an... | ACCEPT | Summary: High-throughput mitochondrial-proteome localization. Correct compartment, consistent with all other localization evidence. |
| GO:0005471 ATP:ADP antiporter activity | ISS GO_REF:0000024 | ACCEPT | Summary: Core MF by sequence similarity to the well-characterized paralog P51881. Correct. |
| GO:0005743 mitochondrial inner membrane | ISS GO_REF:0000024 | ACCEPT | Summary: Core location by similarity to P02722 (bovine ANT). Correct. |
| GO:0005515 protein binding | IPI PMID:31883789 Human-Specific ARHGAP11B Acts in Mitochondria to Expand Neoc... | MARK AS OVER ANNOTATED | Summary: Interaction with the human-specific ARHGAP11B (Q3KRB8), which enters mitochondria and inhibits the mPTP to promote basal-progenitor expansion. A functionally meaningful interaction, but bare "protein binding" is uninformative as an MF; the functional role is captured by the mPTP/apoptosis annotations. Supporting Evidence: PMID:31883789 nucleotide translocase (ANT) and inhibits the mitochondrial permeability |
| GO:0005757 mitochondrial permeability transition pore complex | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: mPTP-complex membership by similarity to P51881. Same unresolved component-vs-regulator status; secondary, non-core. |
| GO:0017077 oxidative phosphorylation uncoupler activity | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Uncoupler activity by similarity to P51881; secondary proton-transport function. Non-core. |
| GO:0030183 B cell differentiation | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: By similarity to P51881; reflects ANT's role in proliferating lymphoid cells. Non-core pleiotropy. |
| GO:0030218 erythrocyte differentiation | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: By similarity to P51881. Context/physiological role, non-core. |
| GO:0046902 regulation of mitochondrial membrane permeability | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: By similarity to P51881; mPTP-linked permeability regulation. Non-core. |
| GO:0140021 mitochondrial ADP transmembrane transport | ISS GO_REF:0000024 | ACCEPT | Summary: Core ADP-import process by similarity to P51881. Correct. |
| GO:1901526 positive regulation of mitophagy | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: Mitophagy regulation by similarity to P51881; secondary, antiport-independent role. Non-core. |
| GO:1990544 mitochondrial ATP transmembrane transport | ISS GO_REF:0000024 | ACCEPT | Summary: Core ATP-export process by similarity to P51881. Correct. |
| GO:1990845 adaptive thermogenesis | ISS GO_REF:0000024 | KEEP AS NON CORE | Summary: By similarity to P51881; downstream of uncoupling. Secondary, non-core. |
| GO:0016020 membrane | IDA PMID:27641616 TSPO ligands stimulate ZnPPIX transport and ROS accumulation... | MARK AS OVER ANNOTATED | Summary: Direct detection of ANT in non-mitochondrial (erythrocyte) membranes; UniProt cites this as evidence that ANT2 may localize to non-mitochondrial membranes. The term is an uninformative high-level parent, but the underlying observation is real. Kept as an over-general location. Supporting Evidence: file:human/SLC25A5/SLC25A5-uniprot.txt May localize to non-mitochondrial |
| GO:0000295 adenine nucleotide transmembrane transporter activity | IMP PMID:19116139 Capsaicin binds to prohibitin 2 and displaces it from the mi... | MODIFY | Summary: The essence (nucleotide transport MF) is correct, but the cited paper is the capsaicin/prohibitin-2 study, which does not measure ANT2 nucleotide-transport activity; and this term is a parent of the specific ATP:ADP antiporter activity. Replace with the specific antiporter MF. Proposed replacements: ATP:ADP antiporter activity |
| GO:0005515 protein binding | IPI PMID:19116139 Capsaicin binds to prohibitin 2 and displaces it from the mi... | MARK AS OVER ANNOTATED | Summary: Co-purification with prohibitin-2 (Q99623) in the capsaicin study. Bare "protein binding" is uninformative as an MF. |
| GO:0051503 adenine nucleotide transport | IMP PMID:19116139 Capsaicin binds to prohibitin 2 and displaces it from the mi... | MODIFY | Summary: Directionally correct (adenine-nucleotide, i.e. ADP/ATP, transport) but weakly supported by the cited capsaicin/prohibitin-2 paper and less specific than the mitochondrial ADP/ATP transmembrane-transport terms. Replace with the specific process. Proposed replacements: mitochondrial ADP transmembrane transport |
| GO:0005515 protein binding | IPI PMID:19130895 Enzymatically inactive adenylate kinase 4 interacts with mit... | MARK AS OVER ANNOTATED | Summary: Interaction with adenylate kinase 4 (AK4, P27144; the annotation also lists prohibitin P21796). Physiologically plausible (both handle adenine nucleotides), but bare "protein binding" is uninformative as an MF. Supporting Evidence: PMID:19130895 interacted with AK4 and higher amount of ANT was |
| GO:0031625 ubiquitin protein ligase binding | IPI PMID:19725078 Proteomic analysis of increased Parkin expression and its in... | KEEP AS NON CORE | Summary: SLC25A5 co-purified as an interactant of the E3 ubiquitin ligase Parkin/PRKN (O60260). A specific, informative binding MF (unlike bare protein binding). Consistent with ANT's role in mitochondrial quality control/mitophagy; retained as a real but non-core interaction. Supporting Evidence: PMID:19725078 SLC25A5, TPI1, UCHL1, UQCRC1, VCL, YWHAZ, YWHAE |
| GO:0016020 membrane | HDA PMID:19946888 Defining the membrane proteome of NK cells. | MARK AS OVER ANNOTATED | Summary: High-throughput membrane-proteome detection (NK-cell membrane proteome). Uninformative high-level parent of the inner-membrane location. |
| GO:0005634 nucleus | HDA PMID:21630459 Proteomic characterization of the human sperm nucleus. | MARK AS OVER ANNOTATED | Summary: From a sperm-nucleus proteome; ANT is an abundant mitochondrial carrier and a common co-purification background hit. Not a bona fide functional nuclear localization for this transporter. Over-annotated. |
| GO:0003723 RNA binding | HDA PMID:22658674 Insights into RNA biology from an atlas of mammalian mRNA-bi... | MARK AS OVER ANNOTATED | Summary: From a high-throughput mRNA-interactome-capture atlas; abundant mitochondrial membrane proteins are frequent nonspecific hits. No evidence that RNA binding is a genuine molecular function of ANT2. Over-annotated. |
| GO:0005739 mitochondrion | HDA PMID:20833797 Phosphoproteome analysis of functional mitochondria isolated... | ACCEPT | Summary: High-throughput detection in the mitochondrial phosphoproteome of human muscle. Correct compartment; a high-level parent of the inner-membrane location. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-163215 | ACCEPT | Summary: Reactome curation of the SLC25A5,6 ADP/ATP exchange reaction at the inner membrane. Correct core location. Supporting Evidence: Reactome:R-HSA-163215 preferentially export ATP from the matrix while importing ADP from the cytosol |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-180905 | ACCEPT | Summary: Reactome (Vpr/ANT association) placing ANT2 at the inner membrane. Correct location; the pathway context (HIV-1 Vpr) is a host-virus interaction, not a core function. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-9837978 | ACCEPT | Summary: Reactome (LONP1 binds inner-membrane proteins) placing ANT2 at the inner membrane. Correct location. |
| GO:0005743 mitochondrial inner membrane | TAS Reactome:R-HSA-9838004 | ACCEPT | Summary: Reactome (LONP1 degrades inner-membrane proteins) placing ANT2 at the inner membrane. Correct location. |
| GO:0008284 positive regulation of cell population proliferation | IMP PMID:19154410 Identification of C2orf18, termed ANT2BP (ANT2-binding prote... | KEEP AS NON CORE | Summary: ANT2 is the historical proliferation-associated ("growth-regulated") ANT isoform; knockdown of its partner ANT2BP suppresses PDAC cell growth. A real but downstream/context-dependent role in proliferating and tumor cells, not the core transport function; retained as non-core. Supporting Evidence: PMID:19154410 suppression of cancer cell growth |
| GO:1901029 negative regulation of mitochondrial outer membrane permeabilization involved in apoptotic signaling pathway | IMP PMID:19154410 Identification of C2orf18, termed ANT2BP (ANT2-binding prote... | KEEP AS NON CORE | Summary: Apoptosis regulation linked to maintenance of mitochondrial membrane potential (ANT2BP knockdown induces apoptosis). Consistent with ANT's mPTP/apoptosis role; secondary and context-specific, non-core. Supporting Evidence: PMID:19154410 resulted in induction of apoptosis and |
| GO:0071817 MMXD complex | IDA PMID:20797633 MMXD, a TFIIH-independent XPD-MMS19 protein complex involved... | KEEP AS NON CORE | Summary: Direct identification of ANT2 as a component of the mitotic spindle-associated MMXD (MMS19-MIP18-XPD) cytosolic iron-sulfur assembly complex implicated in chromosome segregation. A genuine moonlighting role, non-core relative to the inner-membrane antiporter function. Supporting Evidence: PMID:20797633 it included FAM96B (now designated MIP18), Ciao1, and ANT2 |
| GO:0042645 mitochondrial nucleoid | IDA PMID:18063578 The layered structure of human mitochondrial DNA nucleoids. | KEEP AS NON CORE | Summary: ANT co-purifies with mtDNA nucleoid preparations; that study explicitly notes several metabolic proteins in native nucleoids did not cross-link to mtDNA. Most likely an inner-membrane protein associating with membrane-proximal nucleoids rather than a functional nucleoid component. Non-core. |
| GO:0005886 plasma membrane | TAS PMID:2168878 The human fibroblast adenine nucleotide translocator gene. M... | MARK AS OVER ANNOTATED | Summary: The cited paper is only a genomic cloning/sequence of the fibroblast ANT gene and reports no localization assay, so the TAS support is weak. ANT2's residence is the mitochondrial inner membrane; a non-mitochondrial (erythrocyte plasma membrane) pool is documented elsewhere (PMID:27641616), but "plasma membrane" is not a core location for this carrier. |
| GO:0015207 adenine transmembrane transporter activity | TAS PMID:2168878 The human fibroblast adenine nucleotide translocator gene. M... | MODIFY | Summary: Incorrect substrate. ANT transports the adenine nucleotides ADP and ATP, not free adenine (the base). Replace with the specific ATP:ADP antiporter activity. Proposed replacements: ATP:ADP antiporter activity |
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Download this section (compressed HTML)Q: Which of the ANT2-specific phenotypes reported in human cells (mitochondrial permeability transition pore regulation, uncoupling/proton leak, mitophagy) are genuinely isoform-specific, and which are shared properties of the ANT family that have been transferred to SLC25A5 by paralogy?
Q: Is SLC25A5 a structural constituent of the mitochondrial permeability transition pore, or a regulator that modulates a pore formed by other components? The ANT knockout literature supports a regulatory role, but many annotations still read as structural.
Q: Does the reported MMXD (MMS19-MIP18-XPD) complex membership reflect a genuine extramitochondrial pool of ANT2, or co-purification of an abundant inner-membrane carrier? No mechanism links an ADP/ATP antiporter to cytosolic Fe-S cluster trafficking or chromosome segregation.
Q: What accounts for the reciprocal ANT1/ANT2 expression pattern between differentiated and proliferating or glycolytic cells, and does ANT2 operate with a different net directionality (ATP import) under those conditions?
Experiment: Use isogenic SLC25A5 knockout cells, and cells with all three ANT isoforms deleted, reconstituted with transport-dead ANT2 point mutants, then measure calcium-retention capacity, mPTP opening by calcein-cobalt quenching, and swelling in isolated mitochondria. Retention of pore activity in the absence of ANT2, or in the presence of transport-dead ANT2, would separate the regulatory from the structural model.
Hypothesis: SLC25A5 regulates rather than constitutes the mitochondrial permeability transition pore.
Type: isogenic knockout and transport-dead rescue with calcium-retention assays
Experiment: Perform reciprocal immunoprecipitation of MMS19, MIP18 and XPD in cells expressing epitope-tagged ANT2, combined with proximity labelling from a cytosolically exposed bait and with subcellular fractionation controls, to test whether ANT2 is present outside the inner membrane in stoichiometric amounts and whether MMXD assembly survives ANT2 depletion.
Hypothesis: The MMXD complex association of ANT2 is a co-purification artefact rather than a genuine extramitochondrial function.
Type: reciprocal co-IP and proximity labelling with fractionation controls
Experiment: Reconstitute purified recombinant human ANT2 and ANT1 into proteoliposomes and compare ADP/ATP exchange kinetics, membrane-potential dependence and directional bias side by side under matched conditions, then test whether swapping isoforms in cells alters the cytosolic ATP/ADP ratio measured with a genetically encoded sensor.
Hypothesis: SLC25A5 and SLC25A4 differ quantitatively in transport kinetics or directionality, accounting for their reciprocal tissue and proliferative expression.
Type: proteoliposome transport assay with in-cell ATP/ADP sensor readout
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