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-methionine:tRNAMet ligase (AMP-forming).

During oxidative stress, methionine—tRNA ligase might be phosphorylated, which results in promiscuity of this enzyme, where it aminoacylates methionine to various non-Met tRNAs.

This in turn leads to substitution of amino acids in proteins with methionine, which helps relieve oxidative stress in the cell.

[1] As of late 2007, 21 structures have been solved for this class of enzymes, with PDB accession codes 1A8H, 1F4L, 1MEA, 1MED, 1MKH, 1P7P, 1PFU, 1PFV, 1PFW, 1PFY, 1PG0, 1PG2, 1QQT, 1RQG, 1WOY, 2CSX, 2CT8, 2D54, 2D5B, 2DJV, and 2HSN.