Comprehensive Research Report: SLC25A15 (Mitochondrial Ornithine Transporter 1 / ORC1 / ORNT1) Falcon Edison Scientific Literature 40 citations 2 artifacts 2026-07-05T13:56:54.667433

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Comprehensive Research Report: SLC25A15 (Mitochondrial Ornithine Transporter 1 / ORC1 / ORNT1)

1. Gene and Protein Identity

SLC25A15 (Solute Carrier Family 25 Member 15) encodes Mitochondrial Ornithine Transporter 1, also known as Ornithine Carrier 1 (ORC1) or ORNT1 (UniProt: Q9Y619). It is a member of the mitochondrial carrier family (SLC25/TC 2.A.29), a large family of transport proteins embedded in the inner mitochondrial membrane that facilitate the translocation of diverse small molecules between the mitochondrial intermembrane space and the matrix (palmieri2013themitochondrialtransporter pages 3-6). The gene is located on human chromosome 13q14 and encodes a 301 amino acid protein (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).

The following table summarizes the key properties of SLC25A15/ORC1:

Property Summary
Gene name SLC25A15 (solute carrier family 25 member 15) (OpenTargets Search: -SLC25A15, gutierrezaguilar2013physiologicalandpathological pages 3-4)
Aliases ORC1, ORNT1 (gutierrezaguilar2013physiologicalandpathological pages 3-4, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
Protein name Mitochondrial ornithine transporter 1 / ornithine carrier 1 (ORC1) (gao2024cancertherapeuticpotential pages 6-7, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
UniProt ID Q9Y619 (provided target identity)
Chromosomal location 13q14 / chromosome 13 locus reported for human SLC25A15 (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, tessa2009identificationofnovel pages 3-4)
Protein length 301 amino acids (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
Subcellular localization Inner mitochondrial membrane; carrier with N- and C-termini exposed to the cytosolic/intermembrane-space side (tessa2009identificationofnovel pages 5-6, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
Primary substrates L-ornithine, L-citrulline, L-arginine, L-lysine; transport is stereoselective for the L-forms in ORC1 (monne2012substratespecificityof pages 1-2, monne2012substratespecificityof pages 3-4)
Transport mechanism Electroneutral antiport, classically exchanging cytosolic ornithine for matrix citrulline + H+ in a strict 1:1 mode (gao2024cancertherapeuticpotential pages 6-7, monne2012substratespecificityof pages 3-4, palmieri2020diseasescausedby pages 13-15)
Tissue expression Highest/major expression reported in liver, pancreas, lung, kidney; broader tissue expression also noted (gutierrezaguilar2013physiologicalandpathological pages 3-4, ahmed2024theroleof pages 16-18)
Key substrate-binding / mechanistic residues E77, R179, E180 directly contribute to substrate binding; W224 and R275 help couple binding to conformational change/translocation (monne2012substratespecificityof pages 1-2, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, monne2012substratespecificityof pages 7-8)
Structural class Member of the mitochondrial carrier family (SLC25) with 6 transmembrane α-helices and tripartite architecture (tessa2009identificationofnovel pages 5-6, palmieri2013themitochondrialtransporter pages 3-6)
Associated disease Hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome / ornithine translocase deficiency (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, palmieri2020diseasescausedby pages 13-15, OpenTargets Search: -SLC25A15)
Paralogues / related compensatory carriers ORC2 / SLC25A2: 87% identical paralogue with lower affinity and broader substrate range; ORNT3 / SLC25A29: related basic amino acid carrier that can rescue ornithine metabolism in HHH fibroblasts (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 8-9, gutierrezaguilar2013physiologicalandpathological pages 3-4, camacho2009thehumanand pages 6-7)

Table: This table summarizes the core identity, localization, transport properties, structural determinants, disease relevance, and related paralogues of human SLC25A15/ORC1. It is useful as a compact reference for functional annotation and pathway interpretation.

2. Primary Transport Function and Substrate Specificity

SLC25A15/ORC1 functions as an electroneutral antiporter at the inner mitochondrial membrane, catalyzing the 1:1 exchange of cytoplasmic L-ornithine for mitochondrial matrix L-citrulline plus a proton (H+) (palmieri2020diseasescausedby pages 13-15, monne2012substratespecificityof pages 3-4). This transport is the physiologically essential step that bridges the mitochondrial and cytoplasmic segments of the urea cycle (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, cunningham202020000picometersunder pages 4-5). The proton co-transport neutralizes the positive charge of ornithine during the exchange process, rendering the transport electrically neutral (gao2024cancertherapeuticpotential pages 6-7).

The substrate specificity of ORC1 is restricted to the L-forms of ornithine, citrulline, lysine, and arginine (monne2012substratespecificityof pages 1-2). Among these, ORC1 shows highest affinity for L-ornithine, followed by L-arginine and L-lysine (mentel2021learningfromyeast pages 20-21). The stereospecificity for L-isomers is a distinguishing feature of ORC1 compared to ORC2, which can also transport D-isomers and histidine (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 8-9, mentel2021learningfromyeast pages 21-22). ORC1 operates as a strict 1:1 antiporter, meaning it exchanges substrates in a one-to-one stoichiometric ratio across the membrane (monne2012substratespecificityof pages 3-4).

Transport activity has been characterized through reconstitution of bacterially expressed ORC1 protein into proteoliposomes, enabling detailed kinetic and substrate specificity measurements (tessa2009identificationofnovel pages 1-2, tessa2009identificationofnovel pages 3-4).

3. Protein Structure and Transport Mechanism

ORC1 adopts the characteristic tripartite architecture of the SLC25 mitochondrial carrier family, consisting of three tandemly repeated homologous domains, each approximately 100 amino acids in length and containing two hydrophobic transmembrane stretches (palmieri2013themitochondrialtransporter pages 3-6). The protein forms a barrel-like structure composed of six transmembrane α-helices (H1–H6) arranged counter-clockwise that surround a central cavity open toward the cytosolic (intermembrane space) side (tessa2009identificationofnovel pages 5-6, palmieri2013themitochondrialtransporter pages 3-6). Three additional short α-helices (h12, h34, h56) lie parallel to the membrane plane on the matrix side (tessa2009identificationofnovel pages 5-6). Both the N- and C-termini are exposed on the cytosolic side (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).

3.1 Substrate Binding Site

The substrate binding site is located within the central cavity and consists of three major contact points (monne2012substratespecificityof pages 1-2, monne2012substratespecificityof pages 2-3):

Additional residues Asn-74 (N74) and Asn-78 (N78) contribute to the substrate binding pocket (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, monne2012substratespecificityof pages 7-8).

3.2 Gating and Transport Cycle

Transport follows a "single binding center gated pore" model (also described as an alternating-access mechanism) involving opening and closing of gates on the cytoplasmic and matrix sides to alternately expose the common substrate binding site (monne2012substratespecificityof pages 1-2). Three characteristic signature sequence motifs (PFDTMK, PTELVK, and PVDCIK) contain proline residues that kink the odd-numbered transmembrane helices (tessa2009identificationofnovel pages 5-6). A salt-bridge network formed by charged residues (D31-K131, K34-D231, K234-E128) closes the cavity on the matrix side and constitutes the matrix gate (tessa2009identificationofnovel pages 5-6, palmieri2013themitochondrialtransporter pages 3-6). Substrate binding to R179, as the rate-limiting step, triggers conformational changes that open the matrix gate, allowing substrate translocation (monne2012substratespecificityof pages 8-9).

The structural model of ORC1 was built based on the crystal structure of the bovine ADP/ATP carrier (tessa2009identificationofnovel pages 5-6, monne2012substratespecificityof pages 2-3).

4. Role in the Urea Cycle and Ornithine Metabolism

The urea cycle is a metabolic pathway that detoxifies nitrogen by converting ammonia into urea, operating across both the mitochondrial matrix and the cytoplasm of hepatocytes. SLC25A15/ORC1 provides the essential transport link between these two compartments by importing cytoplasmic ornithine into the mitochondrial matrix while simultaneously exporting citrulline to the cytoplasm (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, palmieri2020diseasescausedby pages 13-15, cunningham202020000picometersunder pages 4-5).

In the mitochondrial matrix, imported ornithine serves as a substrate for ornithine transcarbamylase (OTC), which combines ornithine with carbamyl phosphate (produced by carbamoyl phosphate synthetase I) to generate citrulline (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11). The citrulline produced is then exported to the cytoplasm via ORC1, where argininosuccinate synthase reacts citrulline with ATP and aspartate to generate argininosuccinate, continuing the cytoplasmic portion of the urea cycle (cunningham202020000picometersunder pages 4-5).

Beyond the urea cycle, ORC1 also supports arginine biosynthesis and polyamine synthesis, as export of mitochondrial ornithine to the cytosol provides the substrate for ornithine decarboxylase, a key enzyme in polyamine production (mentel2021learningfromyeast pages 20-21, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 8-9).

5. Subcellular Localization and Tissue Expression

ORC1 is an integral membrane protein of the inner mitochondrial membrane (tessa2009identificationofnovel pages 5-6, palmieri2013themitochondrialtransporter pages 3-6). It is expressed broadly across tissues, with highest expression levels reported in liver, pancreas, lung, and kidney (gutierrezaguilar2013physiologicalandpathological pages 3-4, ahmed2024theroleof pages 16-18). Expression in the liver is particularly important given that the urea cycle is principally operative in periportal hepatocytes (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 8-9). Expression has also been noted in testes, small intestine, and other organs (cai2026argininetransportersin pages 10-12, gutierrezaguilar2013physiologicalandpathological pages 3-4).

6. Paralogues and Functional Redundancy

Three human mitochondrial carriers can transport ornithine:

The redundancy provided by ORC2 and SLC25A29 may explain the variable severity and relatively milder phenotypes of HHH syndrome compared to deficiencies in urea cycle enzymes themselves (mentel2021learningfromyeast pages 20-21, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 8-9, arco2005newmitochondrialcarriers pages 10-11).

7. Disease Associations

7.1 HHH Syndrome (Hyperornithinemia-Hyperammonemia-Homocitrullinuria)

Loss-of-function mutations in SLC25A15 cause HHH syndrome (OMIM #238970), a rare autosomal recessive disorder of the urea cycle (palmieri2020diseasescausedby pages 13-15, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11). Over 100 patients have been identified worldwide, with major prevalence clusters in Canada, Italy, and Japan (palmieri2020diseasescausedby pages 13-15). The molecular pathogenesis proceeds through a defined cascade:

  1. Impaired ornithine transport into mitochondria reduces the availability of ornithine for OTC in the matrix (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).
  2. Cytoplasmic ornithine accumulates (hyperornithinemia) while mitochondrial ornithine is depleted (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).
  3. Urea cycle dysfunction leads to ammonia accumulation (hyperammonemia) (palmieri2020diseasescausedby pages 13-15, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).
  4. Accumulated carbamyl phosphate reacts with lysine to form homocitrulline (homocitrullinuria), a hallmark metabolite (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, tunalı2014anovelmutation pages 1-2).
  5. High cytoplasmic ornithine inhibits arginine-glycine amidotransferase (AGAT), causing secondary creatine deficiency, which compounds neurological vulnerability (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).
  6. Excessive ornithine and homocitrulline cause protein and lipid oxidation, impairing brain oxidative phosphorylation and Krebs cycle function (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).

Clinical manifestations include acute episodes of vomiting, confusion, and coma; chronic features include developmental delay, intellectual disability, spastic paraplegia, cerebellar ataxia, seizures, and pyramidal dysfunction (palmieri2020diseasescausedby pages 13-15, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11). More than 35 disease-causing mutations have been identified (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11).

The following table summarizes the spectrum of known pathogenic mutations:

Mutation Type Residual transport activity Structural location Population prevalence / recurrence Functional/pathogenic note
F188del In-frame deletion Defective; markedly reduced activity Likely TM4 / pore region ~30% of reported HHH patients; enriched in French-Canadian cases (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) One of the two most common HHH alleles; affects a residue lining the internal translocation pore, consistent with impaired substrate translocation (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
R179* (also reported as R179X) Nonsense Predicted null Contact-point II / pore-facing region, near matrix gate ~15% of reported HHH patients; recurrent in Japanese and Middle Eastern/Palestinian families (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, tessa2009identificationofnovel pages 3-4, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, dweikat2022clinicalheterogeneityof pages 9-9) Truncates ORC1; residue 179 is a key determinant of substrate recognition in wild-type ORC1, so loss is expected to abolish transport (monne2012substratespecificityof pages 1-2, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
M37R Missense ~0% (virtually incapable of transport) TM1 / matrix salt-bridge network region (H1) (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6) Novel/reported in HHH families; no major founder prevalence stated (tessa2009identificationofnovel pages 6-8) Disrupts salt-bridge networks critical for carrier gating and strongly impairs transport of ornithine, arginine, lysine, and citrulline (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6)
L71Q Missense Reduced; within reported mutant range of ~4–19% of wild type TM2 / H2 helix package (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6) Reported in HHH families; no major founder prevalence stated (tessa2009identificationofnovel pages 6-8) Hydrophilic substitution perturbs H2 helix packing and carrier structural integrity (tessa2009identificationofnovel pages 6-8)
A15V Missense Nearly abolished / dramatically inhibited N-terminal region / early TM1 vicinity (tunalı2014anovelmutation pages 1-2) Identified in a Turkish patient (tunalı2014anovelmutation pages 1-2, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) Functional assay showed near-complete loss of ornithine transport, supporting pathogenicity (tunalı2014anovelmutation pages 1-2)
G27E Missense Defective; exact % not stated TM1 / pore-proximal region Recurrent in Japanese patients; also reported in Palestinian families (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, dweikat2022clinicalheterogeneityof pages 9-9) Associated with decreased ornithine transport activity in liver mitochondria/ORC1 deficiency (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, dweikat2022clinicalheterogeneityof pages 9-9)
G216S Missense Reduced; within reported mutant range of ~4–19% of wild type Likely TM5 / pore-facing region (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6) Reported in HHH families (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 3-4) Alters carrier structure/function and contributes to markedly reduced transport (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6)
T272I Missense Reduced; within reported mutant range of ~4–19% of wild type TM6 region (tessa2009identificationofnovel pages 6-8) Reported in HHH families (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 3-4) Causes steric interference with crucial intramolecular interactions required for catalytic function (tessa2009identificationofnovel pages 6-8)
L283F Missense Reduced; within reported mutant range of ~4–19% of wild type TM6 region / late C-terminal helix (tessa2009identificationofnovel pages 6-8) Reported in HHH families (tessa2009identificationofnovel pages 6-8) Bulky substitution likely perturbs helix packing and transport pathway geometry (tessa2009identificationofnovel pages 6-8)
E180K Missense Pathogenic; exact residual % not stated Contact-point II substrate-binding site near residue R179 (monne2012substratespecificityof pages 1-2, cunningham202020000picometersunder pages 4-5, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11) Reported missense HHH allele (cunningham202020000picometersunder pages 4-5) E180 is a key substrate-binding residue in wild-type ORC1; substitution is expected to disrupt ligand recognition and translocation (monne2012substratespecificityof pages 1-2, martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11)
F188D Missense Pathogenic; exact residual % not stated Around residue 188 in pore/TM4 region (cunningham202020000picometersunder pages 4-5) Reported missense HHH allele (cunningham202020000picometersunder pages 4-5) Missense change near the recurrent F188 hotspot; associated with HHH syndrome and impaired urea-cycle transport (cunningham202020000picometersunder pages 4-5)
P126R Missense Defective; exact % not stated Likely TM3 / central cavity region (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) Reported in affected families (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) Likely disrupts conserved carrier helix geometry important for alternating-access transport (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, tessa2009identificationofnovel pages 5-6)
R275X Nonsense Predicted null TM6 / contact-point III vicinity; R275 is mechanistically important in wild type (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, monne2012substratespecificityof pages 7-8) Reported in affected families (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) Premature stop removes C-terminal region; wild-type Arg275 contributes to substrate-triggered conformational change (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, monne2012substratespecificityof pages 7-8)
T32R Missense Defective; exact % not stated TM1 / matrix-gate neighborhood (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, tessa2009identificationofnovel pages 5-6) Reported in affected families (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16) Likely perturbs local charge environment near matrix-side gating residues (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 16-16, tessa2009identificationofnovel pages 5-6)
p.K245X Nonsense Predicted null C-terminal half / likely TM5-TM6 region (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6) Identified among 13 mutations in HHH families (tessa2009identificationofnovel pages 5-6, tessa2009identificationofnovel pages 3-4) Premature truncation expected to abolish functional carrier assembly/transport (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6)
p.S175fsX192 Frameshift Predicted null Mid-protein / around TM4 entry (tessa2009identificationofnovel pages 5-6) Reported in HHH families (tessa2009identificationofnovel pages 5-6) Frameshift with premature termination; expected severe loss of ORC1 function (tessa2009identificationofnovel pages 5-6)
c.552-555delTTTC (p.Phe185SerfsTer8) Frameshift deletion Predicted null Around residue 185 / pore hotspot region (dweikat2022clinicalheterogeneityof pages 9-9) Novel homozygous variant in 9 Palestinian patients (dweikat2022clinicalheterogeneityof pages 9-9) Expected nonsense-mediated decay or severely truncated protein; expands the HHH molecular spectrum (dweikat2022clinicalheterogeneityof pages 9-9)
c.446delG (p.Ser149ThrfsTer45) Frameshift deletion Predicted null Mid-protein / central carrier region (dweikat2022clinicalheterogeneityof pages 9-9) Recurrent homozygous variant in 4 Palestinian patients (dweikat2022clinicalheterogeneityof pages 9-9) Frameshift expected to abrogate transporter function; associated with marked clinical heterogeneity despite shared genotype (dweikat2022clinicalheterogeneityof pages 9-9)
Overall missense class Missense Typically ~4–19% of wild-type transport, except severe alleles such as M37R (~0%) and A15V (near-abolished) (tessa2009identificationofnovel pages 5-6, tessa2009identificationofnovel pages 1-2, tunalı2014anovelmutation pages 1-2) Frequently in transmembrane helices H1–H6 and residues protruding into the internal pore (tessa2009identificationofnovel pages 6-8, tessa2009identificationofnovel pages 5-6) No clear genotype-phenotype correlation overall (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, tessa2009identificationofnovel pages 1-2) Many pathogenic residues cluster in the translocation pore or gating networks, interfering with substrate binding, helix movement, or conformational switching (martinelli2015thehyperornithinemia–hyperammonemiahomocitrullinuriasyndrome pages 9-11, tessa2009identificationofnovel pages 6-8, monne2012substratespecificityof pages 7-8)

Table: This table summarizes representative disease-causing SLC25A15 variants reported in hyperornithinemia-hyperammonemia-homocitrullinuria syndrome, including mutation class, functional impact, structural context, and recurrence. It is useful for connecting genotype to transporter mechanism and clinical interpretation.

7.2 Cancer Associations

Emerging evidence implicates SLC25A15 in cancer biology in a context-dependent manner:

OpenTargets disease-target association analysis confirms strong associations of SLC25A15 with ornithine translocase deficiency (score 0.85) and HHH syndrome (score 0.84), as well as weaker associations with inflammatory bowel disease and autoimmune CNS disorders (OpenTargets Search: -SLC25A15).

8. Summary

SLC25A15/ORC1 is the principal human mitochondrial ornithine transporter, embedded in the inner mitochondrial membrane, where it catalyzes the electroneutral 1:1 antiport exchange of cytoplasmic L-ornithine for mitochondrial L-citrulline plus a proton. Its primary biological role is to bridge the mitochondrial and cytoplasmic reactions of the urea cycle, ensuring both ornithine availability for OTC in the matrix and citrulline export for argininosuccinate synthase in the cytosol. The protein adopts the canonical six-transmembrane-helix architecture of the SLC25 family, with substrate binding determined by key residues at three contact points (E77, R179/E180, R275). Loss-of-function mutations cause HHH syndrome, a rare urea cycle disorder, while emerging evidence points to context-dependent roles in cancer metabolism. Paralogous carriers ORC2 and SLC25A29 provide partial functional redundancy that may modulate disease severity.

References

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  18. (tessa2009identificationofnovel pages 1-2): Alessandra Tessa, Giuseppe Fiermonte, Carlo Dionisi-Vici, Eleonora Paradies, Matthias R. Baumgartner, Yin-Hsiu Chien, Carmela Loguercio, Helene Ogier de Baulny, Marie-Cecile Nassogne, Manuel Schiff, Federica Deodato, Giancarlo Parenti, S. Lane Rutledge, M. Antonia Vilaseca, Mariarosa A.B. Melone, Gioacchino Scarano, Luiz Aldamiz-Echevarría, Guy Besley, John Walter, Eugenia Martinez-Hernandez, Jose M. Hernandez, Ciro L. Pierri, Ferdinando Palmieri, and Filippo M. Santorelli. Identification of novel mutations in the slc25a15 gene in hyperornithinemia‐hyperammonemia‐homocitrullinuria (hhh) syndrome: a clinical, molecular, and functional study. Human Mutation, 30:741-748, May 2009. URL: https://doi.org/10.1002/humu.20930, doi:10.1002/humu.20930. This article has 88 citations and is from a domain leading peer-reviewed journal.

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Artifacts

Citations

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  2. gao2024cancertherapeuticpotential pages 6-7
  3. monne2012substratespecificityof pages 1-2
  4. mentel2021learningfromyeast pages 20-21
  5. monne2012substratespecificityof pages 3-4
  6. tessa2009identificationofnovel pages 5-6
  7. monne2012substratespecificityof pages 8-9
  8. arco2005newmitochondrialcarriers pages 10-11
  9. camacho2009thehumanand pages 6-7
  10. palmieri2020diseasescausedby pages 13-15
  11. tessa2009identificationofnovel pages 6-8
  12. tunalı2014anovelmutation pages 1-2
  13. dweikat2022clinicalheterogeneityof pages 9-9
  14. ahmed2024theroleof pages 16-18
  15. gutierrezaguilar2013physiologicalandpathological pages 3-4
  16. tessa2009identificationofnovel pages 3-4
  17. monne2012substratespecificityof pages 7-8
  18. mentel2021learningfromyeast pages 21-22
  19. tessa2009identificationofnovel pages 1-2
  20. monne2012substratespecificityof pages 2-3
  21. cai2026argininetransportersin pages 10-12
  22. su2026pufabiflavone pages 12-14
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