O-phosphoseryl-tRNA(Sec) selenium transferase (SEPSECS)

O-phosphoseryl-tRNA(Sec) selenium transferase (SEPSECS) is a pyridoxal phosphate-dependent enzyme essential for the final step in selenocysteine biosynthesis in eukaryotes and archaea[3][1][2][5]. It catalyzes the conversion of O-phosphoseryl-tRNA(Sec) (Sep-tRNA(Sec)) to selenocysteinyl-tRNA(Sec) (Sec-tRNA(Sec)), using selenophosphate as the selenium donor. This reaction is central for recoding select stop codons (UGA) as selenocysteine in selenoproteins during translation. SEPSECS recognizes only the unique structural features of tRNA(Sec). It is one of the autoantigens associated with autoimmune hepatitis (as the soluble liver antigen/liver pancreas antigen, SLA/LP). Loss-of-function mutations are linked to rare neurodevelopmental syndromes such as pontocerebellar hypoplasia type 2D[5][3][1][2]. No approved drugs currently target SEPSECS directly.

Other names

Selenocysteine synthaseSepSecSSLASLA/LPSLA-p35SecSSoluble liver antigenLiver-pancreas antigentRNA(Ser/Sec)-associated antigenic proteinUGA suppressor tRNA-associated proteinSelenocysteinyl-tRNA(Sec) synthaseO-phosphoseryl-tRNA(Sec) selenium transferaseLPPCH2D

Not targeted by drugs; mechanism involves catalyzing the conversion of O-phosphoseryl-tRNA(Sec) to selenocysteinyl-tRNA(Sec) using selenophosphate as selenium donor and pyridoxal phosphate as cofactor[2][3][1][5].