EC Number   |
Natural Substrates |
|---|
    2.9.1.2 | L-phosphoseryl-tRNASec + selenophosphate |
selenocysteine is the only genetically encoded amino acid in humans whose biosynthesis occurs on its cognate transfer RNA (tRNA). O-Phosphoseryl-tRNA:selenocysteinyl-tRNA synthase catalyzes the final step of selenocysteine formation by a tRNA-dependent mechanism |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate |
L-phosphoseryl-tRNA is the crucial precursor for L-selenocysteinyl-tRNA formation in archaea and eukarya. Selenocysteine formation is achieved by a two-step process: O-phosphoseryl-tRNASec kinase (PSTK) phosphorylates the endogenous Ser-tRNASec to O-phosphoseryl-tRNASec, and then this misacylated amino acid-tRNA species is converted to L-selenocysteinyl-tRNASec by Sep-tRNA:Sec-tRNA synthase (SepSecS) |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate |
L-phosphoseryl-tRNA is the crucial precursor for L-selenocysteinyl-tRNA formation in archaea and eukarya. Selenocysteine formation is achieved by a two-step process: O-phosphoseryl-tRNASec kinase phosphorylates the endogenous L-seryl-tRNASec to O-phospho-L-seryl-tRNASec, and then this misacylated amino acid-tRNA species is converted to L-selenocysteinyl-tRNASec by Sep-tRNA:Sec-tRNA synthase |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate |
null mutants of SepSecS abolish selenoprotein synthesis, demonstrating the essentiality of the enzyme for the formation of L-selenocysteinyl-tRNASec. Growth of the knockout strain is not impaired. Thus, unlike mammals, trypanosomes do not require selenoproteins for viability |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate |
SepSecS is a key enzyme required for the synthesis of the trypanosomal selenoproteins. The enzyme does not affect growth of bloodstream forms of Trypanosoma brucei |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate |
the micronutrient selenium is present in proteins as selenocysteine. In eukaryotes and archaea, selenocysteine is formed in a tRNA-dependent conversion of O-phosphoserine by O-phosphoseryltRNA:selenocysteinyl-tRNA synthase |
| 2.9.1.2 | O-phospho-L-seryl-tRNASec + selenophosphate + H2O |
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