Alternative titles; symbols
HGNC Approved Gene Symbol: KYAT3
Cytogenetic location: 1p22.2 Genomic coordinates (GRCh38): 1:88,921,044-88,992,960 (from NCBI)
Kynurenic acid (KYNA), a metabolite of tryptophan, is a broad-spectrum antagonist of excitatory amino acid receptors, suggesting it may participate in normal brain function as a modulator of glutamatergic neurotransmission. The level of KYNA is altered in several neurodegenerative diseases. KAT3 is a kynurenine aminotransferase that forms KYNA by transamination of kynurenine (Yu et al., 2006).
By searching databases for sequences similar to KAT1 (CCBL1; 600547) and KAT2 (AADAT; 611754), followed by PCR of brain cDNA libraries, Yu et al. (2006) cloned mouse and human CCBL2, which they called KAT3. The deduced 454-amino acid human protein has a calculated molecular mass of 51.4 kD and shares 83.7% identity with mouse Kat3. Yu et al. (2006) also identified a human KAT3 splice variant that lacks exon 2 and encodes a deduced 420-amino acid protein. Northern blot analysis of mouse tissues detected strong expression in liver, kidney, and heart, and weaker expression in brain and testis. Expression of Kat3 increased in mouse tissues from postnatal day 7 through 17.
Yu et al. (2006) noted that Kat2 -/- mice have lower hippocampal KYNA levels and are hyperactive compared with wildtype mice, but these abnormalities occur early and are transitory. Yu et al. (2006) found that Kat1 and Kat3 expression, when measured together, was higher in Kat2 -/- mice at postnatal day 60, but not at postnatal days 7, 14, 21, or 28, compared with wildtype mice. The increased Kat1 and Kat3 expression paralleled restoration of the normal phenotype in Kat2 -/- mice. Yu et al. (2006) concluded that upregulation of Kat1 and Kat3 compensates for loss of Kat2 in Kat2 -/- mice.
Yu et al. (2006) determined that the CCBL2 gene contains 14 exons and spans about 143 kb. The first exon is noncoding.
By database analysis, Yu et al. (2006) mapped the CCBL2 gene to chromosome 1p22.2. They mapped the mouse Ccbl2 gene to chromosome 3.
Yu, P., Li, Z., Zhang, L., Tagle, D. A., Cai, T. Characterization of kynurenine aminotransferase III, a novel member of a phylogenetically conserved KAT family. Gene 365: 111-118, 2006. [PubMed: 16376499] [Full Text: https://doi.org/10.1016/j.gene.2005.09.034]