The aminoacyl-tRNA synthetases catalyse the attachment of an amino acid to its cognate transfer RNA molecule in a highly specific two-step reaction.
These proteins differ widely in size and oligomeric state, and have limited sequence homology.
Class I aminoacyl-tRNA synthetases contain a characteristic Rossmann fold catalytic domain and are mostly monomeric.
[2] Class II aminoacyl-tRNA synthetases share an anti-parallel beta-sheet fold flanked by alpha-helices,[3] and are mostly dimeric or multimeric, containing at least three conserved regions.
To date one crystal structure of a glutamyl-tRNA synthetase (Thermus thermophilus) has been solved.