Threonine—tRNA ligase

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threonine-tRNA ligase
EC number
CAS number 9023-46-5
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

In enzymology, a threonine-tRNA ligase (EC is an enzyme that catalyzes the chemical reaction

ATP + L-threonine + tRNAThr AMP + diphosphate + L-threonyl-tRNAThr

The 3 substrates of this enzyme are ATP, L-threonine, and tRNA(Thr), whereas its 3 products are AMP, diphosphate, and L-threonyl-tRNA(Thr).

This enzyme belongs to the family of ligases, to be specific those forming carbon-oxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is L-threonine:tRNAThr ligase (AMP-forming). Other names in common use include threonyl-tRNA synthetase, threonyl-transfer ribonucleate synthetase, threonyl-transfer RNA synthetase, threonyl-transfer ribonucleic acid synthetase, threonyl ribonucleic synthetase, threonine-transfer ribonucleate synthetase, threonine translase, threonyl-tRNA synthetase, and TRS. This enzyme participates in glycine, serine and threonine metabolism and aminoacyl-trna biosynthesis.

Structural studies[edit]

As of late 2007, 17 structures have been solved for this class of enzymes, with PDB accession codes 1EVK, 1EVL, 1FYF, 1KOG, 1NYQ, 1NYR, 1QF6, 1TJE, 1TKE, 1TKG, 1TKY, 1WWT, 1Y2Q, 2HKZ, 2HL0, 2HL1, and 2HL2.


  • ALLEN EH, GLASSMAN E, SCHWEET RS (1960). "Incorporation of amino acids into ribonucleic acid. I. The role of activating enzymes". J. Biol. Chem. 235: 1061–7. PMID 13792726. 
  • HOLLEY RW, BRUNNGRABER EF, SAAD F, WILLIAMS HH (1961). "Partial purification of the threonine- and tyrosine-activating enzymes from rat liver, and the effect of patassium ions on the activity of the tyrosine enzyme". J. Biol. Chem. 236: 197–9. PMID 13715350.