ANT3 Protein
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">ANT3 Protein</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>[SLC25A6](/genes/slc25a6)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>[P12236](https://www.uniprot.org/uniprot/P12236)</td>
</tr>
<tr>
<td class="label">PDB</td>
<td>6G2H</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~33 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Inner mitochondrial membrane</td>
</tr>
</table>
Overview
ANT3 (Adenine Nucleotide Transporter 3), encoded by the SLC25A6 gene on chromosome Xq24, is a member of the solute carrier family 25 (SLC25A) of mitochondrial carriers. Also known as ADP/ATP translocase 3 or mitochondrial ADP,ATP antiporter 3, ANT3 belongs to a family of three adenine nucleotide transporters (ANT1, ANT2, ANT3) that are fundamental to cellular energy metabolism. ANT3 is expressed primarily in tissues with high oxidative capacity and energy demands, including the brain, heart, and skeletal muscle. The protein functions as a homodimer, with each subunit containing six transmembrane helices that form a nucleotide-binding pocket within the inner mitochondrial membrane.
Function and Biology
...ANT3 Protein
<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">ANT3 Protein</th>
</tr>
<tr>
<td class="label">Gene</td>
<td>[SLC25A6](/genes/slc25a6)</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>[P12236](https://www.uniprot.org/uniprot/P12236)</td>
</tr>
<tr>
<td class="label">PDB</td>
<td>6G2H</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~33 kDa</td>
</tr>
<tr>
<td class="label">Localization</td>
<td>Inner mitochondrial membrane</td>
</tr>
</table>
Overview
ANT3 (Adenine Nucleotide Transporter 3), encoded by the SLC25A6 gene on chromosome Xq24, is a member of the solute carrier family 25 (SLC25A) of mitochondrial carriers. Also known as ADP/ATP translocase 3 or mitochondrial ADP,ATP antiporter 3, ANT3 belongs to a family of three adenine nucleotide transporters (ANT1, ANT2, ANT3) that are fundamental to cellular energy metabolism. ANT3 is expressed primarily in tissues with high oxidative capacity and energy demands, including the brain, heart, and skeletal muscle. The protein functions as a homodimer, with each subunit containing six transmembrane helices that form a nucleotide-binding pocket within the inner mitochondrial membrane.
Function and Biology
ANT3 catalyzes the electroneutral exchange of ADP and ATP across the inner mitochondrial membrane through an antiport mechanism. This bidirectional transport couples the extrusion of ATP (synthesized by ATP synthase in the mitochondrial matrix) with the import of ADP (needed for continued ATP production). This exchange is critical because it maintains the ATP/ADP ratio within the mitochondrial matrix, sustaining oxidative phosphorylation and the chemiosmotic gradient necessary for ATP synthesis. The transport process is driven by the membrane potential (positive inside) and represents one of the most abundant transport activities in mitochondria, accounting for approximately 5-10% of total protein content in energetically active tissues.
The three ANT isoforms display distinct tissue distribution patterns and regulatory properties. ANT1 predominates in skeletal muscle and heart, ANT2 is ubiquitously expressed at lower levels, and ANT3 is primarily expressed in the central and peripheral nervous systems. This differential expression suggests specialized roles in neurons and other tissues with high ATP demand. ANT proteins also exhibit sensitivity to various metabolic regulators, including fatty acids and thyroid hormones, which can modulate their activity in response to cellular energy status.
Role in Neurodegeneration
The integrity of mitochondrial bioenergetics is paramount in neuronal survival, given that neurons are exceptionally metabolically active cells with limited glycolytic capacity and high reliance on oxidative phosphorylation. Compromise of ANT3 function directly impairs mitochondrial ATP export, leading to intracellular energy depletion. Several neurodegenerative conditions involve dysfunction of mitochondrial transporters, and ANT3 dysfunction has been implicated in mechanisms underlying neuronal cell death in various contexts.
Mutations in SLC25A6 have been identified in families with X-linked forms of combined oxidative phosphorylation deficiency (COXPD) and infantile myopathy with lactic acidosis. Neurological manifestations include developmental delay, seizures, and progressive neurodegeneration. Additionally, ANT3 dysfunction contributes to age-related neurodegeneration through accumulated mitochondrial dysfunction, reduced ATP availability, and enhanced vulnerability to excitotoxic insults. The protein's role in maintaining ATP homeostasis connects its dysfunction to both acute neurological injury and chronic neurodegenerative processes.
Molecular Mechanisms
ANT3 dysfunction in neurodegeneration operates through several interconnected mechanisms. Reduced ADP/ATP exchange capacity decreases mitochondrial ATP export, impairing ATP-dependent processes including ion pump function, protein synthesis, and synaptic transmission. This energetic deficit compromises the maintenance of cellular ion gradients, leading to calcium dysregulation, excitotoxicity, and activation of apoptotic pathways. Impaired ANT3 function also promotes accumulation of mitochondrial ROS (reactive oxygen species) through disrupted electron transport chain equilibrium and reduced metabolic efficiency.
Certain mutations in SLC25A6 impair the stability, trafficking, or catalytic efficiency of ANT3. Damaged or misfolded ANT3 may trigger mitochondrial unfolded protein responses and contribute to formation of the mitochondrial permeability transition pore (mPTP), leading to mit
AlphaFold Structure
AlphaFold DB provides a predicted structure for SLC25A6 / UniProt P12236 (model version 6): https://alphafold.ebi.ac.uk/entry/P12236.
AlphaFold reports a mean pLDDT confidence score of 92.38, indicating very high average confidence.
InterPro annotations highlight Mitochondrial carrier protein family (11-24); ADP/ATP carrier protein, eukaryotic type family (4-297); Mitochondrial carrier protein, transmembrane region repeat (6-100).
PDB coordinates: https://alphafold.ebi.ac.uk/files/AF-P12236-F1-model_v6.pdb mmCIF coordinates: https://alphafold.ebi.ac.uk/files/AF-P12236-F1-model_v6.cif.
Use the prediction as structural context for target assessment; local low-pLDDT segments may reflect disorder, flexible linkers, or unresolved domain orientation rather than a stable fold.