In enzymology, a cysteineâÂÂtRNA ligase () is an enzyme that catalyzes the chemical reaction:
The three substrates of this enzyme are ATP, -cysteine, and tRNA, whereas its three products are AMP, diphosphate, and -cysteinyl-tRNA.
This enzyme belongs to the family of ligases, specifically those forming carbonâÂÂoxygen bonds in aminoacyl-tRNA and related compounds. The systematic name of this enzyme class is -cysteine:tRNA ligase (AMP-forming). Other names in common use include cysteinyl-tRNA synthetase, cysteinyl-transferRNA synthetase, cysteinyl-transfer ribonucleate synthetase, and cysteine translase. This enzyme participates in cysteine metabolism and aminoacyl-tRNA biosynthesis.
As of late 2007, three structures have been solved for this class of enzymes, with PDB accession codes , , and .