The Mitochondrial Ornithine Carrier 1 (ORC1) protein is encoded by the SLC25A15 (solute carrier family 25, member 15) gene located on chromosome 13q14. ORC1 protein catalyzes the transport of cytosolic ornithine across the inner mitochondrial membrane, from the cytoplasm to the matrix, where it participates in the urea cycle and functions in ammonium detoxification and biosynthesis of the amino acid arginine.
Defects in the ORC1 protein are associated with Hyperornithinemia-Hyperammonemia-Homocitrullinuria syndrome, an autosomal recessive disorder resulting in various neurologic symptoms, including mental retardation, spastic paraparesis with pyramidal signs, cerebellar ataxia, and episodic disturbance of consciousness or coma caused by hyperammonemia.