18. The anticodon and/or the amino acid arms of a tRNA are key for a specific aminoacyl-tRNa synthetase to recognize This was revealed via: crystal structure determination of the synthetases complexed with their cognate tRNAS, sequence comparison of trnas binding to the same synthetase and mutagenesis studies When the anticodon of tRNAVal is changed from UaC to cau. the mutated tRNAVal can be recognized by Met-tRNa synthetase and generating a met-tRNAvVal18. The anticodon and/or the amino acid arms of a tRNA are key for a specific aminoacyl-tRNA synthetase to recognize • This was revealed via: crystal structure determination of the synthetases complexed with their cognate tRNAs; sequence comparison of tRNAs binding to the same synthetase; and mutagenesis studies. • When the anticodon of tRNAVal is changed from UAC to CAU, the mutated tRNAVal can be recognized by Met-tRNA synthetase and generating a Met-tRNAVal