Mitochondrial Carrier ATA-1 Protein

Mitochondrial Carrier ATA-1 Protein

Introduction

Mitochondrial Carrier Ata 1 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein"> [@hediger2013]
<table> [@kmiec2006]
<tr><th colspan="2" style="background:#4477AA; color:white; text-align:center">SLC25A15</th></tr> [@fiermonte2004]
<tr><th>Protein Name</th><td>Mitochondrial Carrier ATA-1</td></tr> [@rutishauser2012]
<tr><th>Gene</th><td>[SLC25A15](/genes/slc25a15)</td></tr>
<tr><th>UniProt ID</th><td>[Q9Y3D0](https://www.uniprot.org/uniprot/Q9Y3D0)</td></tr>
<tr><th>PDB IDs</th><td>6G7V, 7BRS</td></tr>
<tr><th>Molecular Weight</th><td>33.8 kDa</td></tr>
<tr><th>Subcellular Localization</th><td>Mitochondrial Inner Membrane</td></tr>
<tr><th>Protein Family</th><td>Mitochondrial Carrier Family (MCF)</td></tr>
</table>
</div>

Overview

Mitochondrial Carrier ATA-1 (also known as ORNT1, SLC25A15) is a mitochondrial carrier protein that transports amino acids across the inner mitochondrial membrane. It plays a crucial role in the urea cycle and mitochondrial metabolism. Mutations in the SLC25A15 gene cause the rare metabolic disorder Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH) syndrome, characterized by neurological symptoms.

Structure

...

Mitochondrial Carrier ATA-1 Protein

Introduction

Mitochondrial Carrier Ata 1 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein"> [@hediger2013]
<table> [@kmiec2006]
<tr><th colspan="2" style="background:#4477AA; color:white; text-align:center">SLC25A15</th></tr> [@fiermonte2004]
<tr><th>Protein Name</th><td>Mitochondrial Carrier ATA-1</td></tr> [@rutishauser2012]
<tr><th>Gene</th><td>[SLC25A15](/genes/slc25a15)</td></tr>
<tr><th>UniProt ID</th><td>[Q9Y3D0](https://www.uniprot.org/uniprot/Q9Y3D0)</td></tr>
<tr><th>PDB IDs</th><td>6G7V, 7BRS</td></tr>
<tr><th>Molecular Weight</th><td>33.8 kDa</td></tr>
<tr><th>Subcellular Localization</th><td>Mitochondrial Inner Membrane</td></tr>
<tr><th>Protein Family</th><td>Mitochondrial Carrier Family (MCF)</td></tr>
</table>
</div>

Overview

Mitochondrial Carrier ATA-1 (also known as ORNT1, SLC25A15) is a mitochondrial carrier protein that transports amino acids across the inner mitochondrial membrane. It plays a crucial role in the urea cycle and mitochondrial metabolism. Mutations in the SLC25A15 gene cause the rare metabolic disorder Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH) syndrome, characterized by neurological symptoms.

Structure

Mitochondrial carriers share a common structural fold:

• Three Mitochondrial Carrier Domains: Each ~100 amino acids
• Six Transmembrane α-Helices: Form the transport channel
• Three Internal Repeats: Symmetric three-fold symmetry
• Matrix-facing and Intermembrane Space-facing Gates: Regulate substrate transport

Key structural features:

• PXD motif: Proline-X-Aspartate in each repeat
• Carrier-specific substrate-binding site
• Salt bridge network: For substrate recognition

Normal Function

Transport Activities

• Ornithine Transport: Exchanges ornithine with citrulline across the inner membrane
• Lysine Transport: Low affinity for basic amino acids
• Histidine Transport: Minor substrate

Physiological Roles

• Urea Cycle: Links mitochondrial and cytosolic portions
• Amino Acid Metabolism: Regulates mitochondrial amino acid pools
• Nitric Oxide Synthesis: Provides substrate for argininosuccinate synthesis

Expression Pattern

SLC25A15 expression:

• Liver: High expression in hepatocytes (urea cycle)
• Kidney: Moderate expression
• Brain: Neuronal expression, higher in certain regions
• Intestine: Moderate expression
• Pancreas: Low expression

Role in Neurodegeneration

HHH Syndrome

• Gene: Autosomal recessive SLC25A15 mutations
• Phenotype: Hyperornithinemia, hyperammonemia, homocitrullinuria
• Neurological Symptoms: Developmental delay, ataxia, seizures
• Treatment: Dietary protein restriction, ammonia scavengers

General Neurodegeneration

• Mitochondrial Dysfunction: Energy metabolism defects
• Ammonia Toxicity: In HHH syndrome, hyperammonemia damages [neurons](/entities/neurons)
• Oxidative Stress: Impaired mitochondrial function

Potential Links

• Altered Ornithine Metabolism: May affect polyamine synthesis
• Mitochondrial Energy Defects: Common in neurodegeneration

Therapeutic Implications

Drug Development

• Enzyme Replacement: Not applicable (transport protein)
• Gene Therapy: Potential for HHH syndrome
• Small Molecule Modulators: Experimental

Clinical Management

• HHH Syndrome Treatment:
• Protein restriction
• Ammonia scavengers (sodium phenylbutyrate)
• Arginine supplementation
• Ornithine supplementation

Research Directions

Understanding substrate specificity

Developing treatments for HHH syndrome

Mitochondrial carrier modulation for neurodegeneration

Biomarkers for mitochondrial transport function

Background

The study of Mitochondrial Carrier Ata 1 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

Disease Mechanisms

HHH Syndrome Pathogenesis

The HHH syndrome (Hyperornithinemia-Hyperammonemia-Homocitrullinuria) results from impaired ornithine transport across the mitochondrial membrane. This leads to:

• Energy- Neuroinflammation**: Astrocyte dysfunction

Animal Models

Mouse Models

• Slc25a15 Knockout: Recapitulates HHH syndrome
• Phenotype: Hyperammonemia, ornithine accumulation, ataxia
• Therapeutic Testing: Dietary interventions, gene therapy

Cellular Models

• Fibroblast Studies: From HHH patients
• Transport Assays: Measuring ornithine flux
• Metabolomic Analysis: Metabolic profiling

Diagnostic Testing

Biochemical Markers

• Plasma Ornithine: Elevated (hyperornithinemia)
• Urinary Homocitrulline: Elevated
• Blood Ammonia: Elevated (hyperammonemia)
• Orotic Aciduria: Variable

Genetic Testing

• SLC25A15 Sequencing: Confirms diagnosis
• Carrier Testing: Family members
• Prenatal Testing: For at-risk pregnancies

Prognosis and Management

Long-term Outcomes

• Early treatment improves neurological outcomes
• Dietary compliance essential
• Risk of acute hyperammonemic crises

Current Therapies

• Dietary Protein Restriction: Essential amino acid limitation
• Ammonia Scavengers: Sodium phenylbutyrate, glycerol phenylbutyrate
• L-Citrulline Supplementation: Bypasses transport defect
• L-Ornithine Supplementation: May help in some cases
• Liver Transplantation: For severe cases

Future Directions

See A

• Mitochondrial Carriers - Category
• Mitochondrial - Parkinson'- Alzheimer's Disease - Alzheimer's disease
• [UniProt: Q9Y2R4](https://www.uniprot.org/uniprot/Q9Y2R4) - SLC25A23 protein entr

References

[Unknown, Palmieri F (2008). The mitochondrial carrier family (2008)](https://pubmed.ncbi.nlm.nih.gov/18421548/)

[Hediger MA, et al, (2013) (2013)](https://pubmed.ncbi.nlm.nih.gov/23657939/)

[Kmiec B, et al, (2006) (2006)](https://pubmed.ncbi.nlm.nih.gov/16550548/)

[Fiermonte G, et al, (2004) (2004)](https://pubmed.ncbi.nlm.nih.gov/15554355/)

[Unknown, Rutishauser J (2012). Mitochondrial carrier proteins (2012)](https://pubmed.ncbi.nlm.nih.gov/22633972/)