Description
In eukarya an additional guanosine residue is added post-transcriptionally to the 5'-end of tRNAHis molecules. The addition occurs opposite a universally conserved adenosine73 and is thus the result of a non-templated 3'-5' addition reaction. The additional guanosine residue is an important determinant for aminoacylation by EC 6.1.1.21, histidyl-tRNA ligase.The enzyme requires a divalent cation for activity. ATP activation is not required when the substrate contains a 5'-triphosphate (ppp-tRNAHis)