Alternative titles; symbols
HGNC Approved Gene Symbol: THNSL2
Cytogenetic location: 2p11.2 Genomic coordinates (GRCh38): 2:88,170,346-88,186,627 (from NCBI)
Donini et al. (2006) searched sequence databases to identify proteins that encode possible threonine synthases (TS) and identified 2, which they designated TSH1 (611260) and TSH2, in several species, including humans and mice. Alternative splicing results in several deduced human TSH2 proteins, the longest of which contains 405 amino acids. EST database analysis indicated expression of both TSH1 and TSH2. In mouse, TSH2 transcripts are most abundant in the kidney and liver, whereas TSH1 transcripts are mainly seen in the brain and endocrine glands. The mouse TSH2 protein is 38% identical to S. cerevisiae threonine synthase.
Donini et al. (2006) determined that TSH2 contains 7 introns in humans and mice. Human TSH2 appears to undergo differential splicing, producing several possible proteins.
Donini et al. (2006) found that recombinant mouse TSH2 bound pyridoxal-5-prime phosphate (PLP), but did not synthesize L-threonine. TSH2 did, however, bind O-phospho-homoserine (PHS), the actual TS substrate, and degraded it to alpha-ketobutyrate, phosphate, and ammonia--a known side reaction of microbial threonine synthases. Donini et al. (2006) pointed out that the binding to PHS has no metabolic relevance since PHS is not formed in animal metabolism. Instead, they proposed that TSH2 may be involved in the catabolism of phosphothreonine (PThr), a product possibly produced by the degradation of phosphorylated proteins.
Donini et al. (2006) suggested an unusual evolutionary origin for TSH2, whereby an original TS enzyme became 'recycled' into a phospho-lyase upon dismissal, in metazoa, of the L-Thr biosynthetic pathway.
Scott (2007) mapped the THNSL2 gene to chromosome 2p11.2 based on an alignment of the THNSL2 sequence (GenBank AK095303) with the genomic sequence (build 36.2).
Donini, S., Percudani, R., Credali, A., Montanini, B., Sartori, A., Peracchi, A. A threonine synthase homolog from a mammalian genome. Biochem. Biophys. Res. Commun. 350: 922-928, 2006. [PubMed: 17034760] [Full Text: https://doi.org/10.1016/j.bbrc.2006.09.112]
Scott, A. F. Personal Communication. Baltimore, Md. 7/17/2007.