TRNA(His) guanylyltransferase

tRNA(His) guanylyltransferase (, "histidine tRNA guanylyltransferase", "Thg1p", "Thg1") is an enzyme with systematic name "p-tRNA(His):GTP guanylyltransferase (ATP-hydrolysing)". This enzyme catalyses the following chemical reaction
The enzyme requires a divalent cation for activity.