GATC allows the formation of correctly charged Gln-tRNA(Gln) through the transamidation of misacylated Glu-tRNA(Gln) in the mitochondria. The reaction takes place in the presence of glutamine and ATP through an activated gamma-phospho-Glu-tRNA(Gln). This protein is subunit of the heterotrimeric GatCAB amidotransferase (AdT) complex, composed of A (QRSL1), B (PET112) and C (GATC) subunits. Recombinant human GATC protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.