Kynurenine—glyoxylate transaminase

Kynurenine—glyoxylate transaminase (KGT), also known as kynurenine aminotransferase III (KAT III), is an enzyme that in humans is encoded by the CCBL1 gene. This enzyme plays a crucial role in the metabolism of tryptophan, an essential amino acid, by catalyzing the transamination of kynurenine to kynurenic acid (KYNA) in the presence of glyoxylate, thus participating in the kynurenine pathway of tryptophan degradation.

Function

Kynurenine—glyoxylate transaminase is involved in the kynurenine pathway, which is responsible for converting tryptophan to nicotinamide adenine dinucleotide (NAD+). The pathway is a major route of tryptophan catabolism, leading to the production of several bioactive metabolites, including kynurenic acid, which is a neuroprotective agent. KGT catalyzes the transamination of kynurenine to kynurenic acid, a critical step in the regulation of the levels of these metabolites in the brain and other tissues. Kynurenic acid acts as an antagonist at excitatory amino acid receptors and is involved in various physiological processes, including neuroprotection, modulation of neurotransmitter release, and regulation of immune responses.

Clinical Significance

Alterations in the kynurenine pathway have been implicated in a variety of diseases, including psychiatric disorders such as schizophrenia and depression, neurodegenerative diseases like Huntington's and Alzheimer's disease, and inflammatory diseases. Due to its role in the production of kynurenic acid, KGT is of interest as a potential therapeutic target. Modulating KGT activity could influence the levels of kynurenic acid and other metabolites, offering possible interventions for diseases associated with dysregulation of the kynurenine pathway.

Genetics

The CCBL1 gene encodes the Kynurenine—glyoxylate transaminase enzyme. Variants and mutations in this gene may affect the enzyme's function and have been studied in the context of their potential link to disease states, particularly those involving alterations in tryptophan metabolism.

See Also

• Kynurenine pathway
• Tryptophan metabolism
• Neurotransmitter
• Neuroprotection