Table of Contents - *600902
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Genome
DNA
Protein
Gene Info
Variation
Animal Models
Cellular Pathways
| *600902 | ||||||||||
| SELENOPHOSPHATE SYNTHETASE 1; SEPHS1 | ||||||||||
| Alternative titles; symbols | ||||||||||
| SPS1 | ||||||||||
| HGNC Approved Gene Symbol: SEPHS1 | ||||||||||
| Cytogenetic location: 10p13 Genomic coordinates (GRCh37): 10:13,359,437 - 13,390,297 (from NCBI) | ||||||||||
| TEXT | ||||||||||
| Cloning | ||||||||||
| Selenocysteine is co-translationally incorporated into prokaryotic and eukaryotic selenoproteins at in-frame UGA codons. Low et al. (1995) noted that, in bacteria, 4 genes are required for selenocysteine codon recognition and translation. In eukaryotes, the selenocysteine-specific tRNA (165060) was the first component of the selenocysteine incorporation machinery to be identified. In prokaryotes, selenophosphate is the active selenium donor and is synthesized from selenide and ATP by the product of the so-called selD gene, selenophosphate synthetase. Low et al. (1995) cloned the human homolog of selD. The authors observed that human selenophosphate synthetase had only 32% homology with the bacterial protein. Tamura et al. (2004) cloned SPS1 and SPS2 (606218) from a cDNA library prepared from human lung adenocarcinoma cells. Human lung SPS1 was cloned as an open reading frame (ORF) of 1,179 bp, identical in sequence to that of human liver SPS1. | ||||||||||
| Gene Function | ||||||||||
| Low et al. (1995) showed that transfection of human selD cDNA into mammalian cells resulted in increased selenium labeling of a mammalian protein, type I iodothyronine deiodinase (147892). Despite significant differences between the mechanisms of selenoprotein synthesis in prokaryotes and eukaryotes, human selD weakly complemented a bacterial selD mutation, partially restoring selenium incorporation into bacterial selenoproteins. A labile selenium donor compound monoselenophosphate is synthesized from selenide and ATP by selenophosphate synthetase (SPS). Tamura et al. (2004) altered the in-frame TGA codon of lung SPS2 to TGT (cys); the resulting gene was designated SPS2cys. Expression of the recombinant plasmids containing SPS1 or SPS2cys was highly toxic to E. coli host cells grown aerobically. Accordingly, the human lung SPS homologs were characterized by an in vivo complementation assay using a selD mutant strain of E. coli. These studies suggested an apparent substrate specificity of the SPS1 and SPS2 gene products, leading Tamura et al. (2004) to suggest that the SPS1-encoded enzyme depends on a selenium salvage system that recycles L-selenocysteine, whereas the SPS2 enzyme can function with a selenite assimilation system. | ||||||||||
| Mapping | ||||||||||
| Gross (2011) mapped the SEPHS1 gene to chromosome 10p13 based on an alignment of the SEPHS1 sequence (GenBank BC000941) with the genomic sequence (GRCh37). | ||||||||||
| REFERENCES | ||||||||||
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