L-ornithine transmembrane transport

Definition

Target type: biologicalprocess

The directed movement of L-ornithine across a membrane. [GO_REF:0000069, GOC:krc, GOC:TermGenie, PMID:8195186]

L-ornithine transmembrane transport is a fundamental process in cellular metabolism, enabling the movement of L-ornithine across cell membranes. This process is crucial for various physiological functions, including:

1. **Urea Cycle:** L-ornithine is a key intermediate in the urea cycle, the primary pathway for ammonia detoxification in mammals. The efficient transport of L-ornithine across mitochondrial membranes is essential for the proper functioning of this pathway.

2. **Polyamine Synthesis:** L-ornithine serves as a precursor for the biosynthesis of polyamines, which are essential for cell growth, proliferation, and differentiation. The transport of L-ornithine into the cytoplasm facilitates polyamine synthesis.

3. **Amino Acid Metabolism:** L-ornithine is involved in the metabolism of other amino acids, including arginine and proline. Its transport across membranes allows for the interconversion of these amino acids.

4. **Regulation of Intracellular pH:** L-ornithine transport can contribute to the regulation of intracellular pH by influencing the movement of protons across membranes.

The mechanism of L-ornithine transmembrane transport is complex and involves several different transporters. Key transporters include:

1. **System y+L:** This transporter is a sodium-dependent, electroneutral system that primarily transports L-arginine and L-lysine but also exhibits affinity for L-ornithine. It is found in the plasma membrane of various cell types, including intestinal epithelial cells and hepatocytes.

2. **Orn/Arg Transporter (OAT):** This transporter is responsible for the bidirectional transport of L-ornithine and L-arginine across the mitochondrial membrane. It plays a crucial role in the urea cycle and polyamine synthesis.

3. **Other Transporters:** Other transporters, such as the cationic amino acid transporter (CAT) and the L-ornithine transporter (OrnT), may also contribute to L-ornithine transport in specific tissues.

The activity of these transporters is regulated by various factors, including substrate concentration, pH, and the presence of inhibitors. The specific mechanism of regulation varies depending on the transporter and the cell type.

In summary, L-ornithine transmembrane transport is a vital process that enables the movement of this essential amino acid across cell membranes. This process is essential for various physiological functions, including ammonia detoxification, polyamine synthesis, amino acid metabolism, and the regulation of intracellular pH. The transport process is facilitated by specialized transporters that exhibit specific affinities for L-ornithine and are subject to complex regulation.'
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Proteins (1)

Compounds (2)