The Mitochondrial Ornithine Transporter
Open accessAbstract
Two isoforms of the human ornithine carrier, ORC1 and ORC2, have been identified by overexpression of the proteins in bacteria and by study of the transport properties of the purified proteins reconstituted into liposomes. Both transport L-isomers of ornithine, lysine, arginine, and citrulline by exchange and by unidirectional mechanisms, and they are inactivated by the same inhibitors. ORC2 has a broader specificity than ORC1, and L- and D-histidine, L-homoarginine, and D-isomers of ornithine, lysine, and ornithine are all substrates. Both proteins are expressed in a wide range of human tissues, but ORC1 is the predominant form. The highest levels of expression of both isoforms are in the liver. Five mutant forms of ORC1 associated with the human disease hyperornithinemia-hyperammonemia-homocitrullinuria were also made. The mutations abolish the transport properties of the protein. In patients with hyperornithinemia-hyperammonemia-homocitrullinuria, isoform ORC2 is unmodified, and its presence compensates partially for defective ORC1.
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SLC25A15 is an ornithine transporter in the urea cycle.
“SLC25A15, is an ornithine transporter in the urea cycle38”
From Spatial transcriptomics of healthy and fibrotic human liver at single-cell resolution (2025) · cites this paper as [38]
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- Krebs, H.A., Lund, P., and Stubbs, M. (1976) in Gluconeogenesis (Hanson, R.W. and Mehlman, M.A., eds.) pp. 269-292, Academic Press, New York
- Kuo, F.C., Hwu, W.L., Valle, D., and Darnell, J.E.Jr (1991) Proc. Natl. Acad. Sci. USA 8 8, 9 4 6 8 -9 4 7 2
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- Authors
- Fiermonte, G., Dolce, V., David, L., Santorelli, F. M., Dionisi-Vici, C., Palmieri, F., & Walker, J. E.
- Affiliations
- University of Bari Aldo Moro (IT)
- University of Calabria (IT)
- Bambino Gesù Children's Hospital (IT)
- MRC Mitochondrial Biology Unit (GB)
- Corresponding author
- Palmieri, Ferdinando
- Walker, John E.
- Venue
- Journal of Biological Chemistry
- Publisher
- Elsevier BV
- Published
- 2003-08
- Volume
- 278
- Issue
- 35
- Pages
- 32778-32783
- ISSN
- 0021-9258 (ISSN-L)
- OpenAlex
- W2061768950
- Cited by
- 140
- References
- 0
- Citations by year
- 2026: 3 · 2025: 8 · 2024: 7 · 2023: 5 · 2022: 1 · 2021: 5 · 2020: 11 · 2019: 5 · 2018: 6 · 2017: 3 · 2016: 3 · 2015: 8 · 2014: 9 · 2013: 7 · 2012: 9
- FWCI
- 3.66
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Journal of Biological Chemistry (publishedVersion, cc-by)
- PubMed (publishedVersion)
- Archive of Doctoral Theses and Digital Collections (University of Calabria) (submittedVersion)
- CINECA IRIS Institutional Research Information System (University of Bari Aldo Moro) (submittedVersion)
- INFM-OAR (INFN Catania) (submittedVersion, cc-by)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Amino Acid Enzymes and Metabolism
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Clinical Biochemistry › Metabolism and Genetic Disorders
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Polyamine Metabolism and Applications
- Keywords
- ORC1, ORC2, lysine transport, arginine transport, histidine transport, homoarginine, transport specificity, transport inhibitors, pathogenic variants, liver
- MeSH terms
- Arginine, Biological Transport, Carrier Proteins, Citrulline, Electrophoresis, Polyacrylamide Gel, Humans, Kinetics, Liposomes, Liver, Lysine, Malates, Mitochondria, Models, Biological, Mutation, Ornithine, Phosphates, Recombinant Proteins, Substrate Specificity, Time Factors, Tissue Distribution, Transcription, Genetic, Protein Folding, DNA, Complementary, Protein Isoforms, Reverse Transcriptase Polymerase Chain Reaction, Hyperammonemia, Membrane Transport Proteins, Amino Acid Transport Systems, Basic
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