Phosphoseryl-tRNA kinase (PSTK)

Phosphoseryl-tRNA kinase (PSTK) is a specialized enzyme essential for the biosynthesis of selenocysteine, the 21st amino acid, in eukaryotes and archaea [PubMed: 15145950]. It catalyzes the ATP-dependent phosphorylation of L-seryl-tRNA(Sec) to form O-phospho-L-seryl-tRNA(Sec), which is a mandatory intermediate for the subsequent conversion to selenocysteinyl-tRNA(Sec) by selenocysteine synthase [UniProt: Q8IV42]. This pathway is critical because selenocysteine is synthesized on its cognate tRNA rather than being loaded directly by an aminoacyl-tRNA synthetase. Selenoproteins, which incorporate this amino acid, play vital roles in antioxidant defense, thyroid hormone metabolism, and redox signaling [NCBI Gene: 118672]. While PSTK is not currently a primary target for approved drugs, its fundamental role in selenoprotein synthesis makes it a subject of interest in research regarding metabolic disorders and oxidative stress-related diseases [PubMed: 15145950].

Other names

L-seryl-tRNA(Sec) kinaseSer-tRNA(Sec) kinasePhosphoseryl-tRNA[Ser]Sec kinasePSTK

Catalyzes the ATP-dependent phosphorylation of L-seryl-tRNA(Sec) to O-phospho-L-seryl-tRNA(Sec), which is a required intermediate for selenocysteine synthesis [UniProt: Q8IV42].