EC Number   |
Natural Substrates |
|---|
   2.7.7.79 | p-ctRNAHis + ATP + GTP + H2O |
cytoplasmic tRNAHis |
| 2.7.7.79 | p-mtRNAHis + ATP + GTP + H2O |
mitochondrial tRNAHis |
| 2.7.7.79 | p-tRNAHis + ATP + GTP |
the extra nucleotide in position -1 of mitochondrial and eukaryotic cytoplasmic tRNAHis molecules is added posttranscriptionally to the 5' end of the tRNA by a histidine-tRNA specific guanylyltransferase |
| 2.7.7.79 | p-tRNAHis + ATP + GTP |
- |
| 2.7.7.79 | p-tRNAHis + ATP + GTP |
all tRNAHis possess an essential extra GĀ1 guanosine residue at their 5' end. This extra guanylate residue can be generated via two different processes. In Escherichia coli and in chloroplasts, the GĀ1 is genome-encoded and retained during tRNA maturation because of an unusual cleavage of the pre-tRNAHis at the (-1) position by RNase P. In Saccharomyces cerevisiae as well as in Drosophila melanogaster the GĀ1 is not genome-encoded and must be post-transcriptionally added at the 5' terminus of the nuclear-encoded tRNAHis by a specific tRNAHis guanylyltransferase. In plant mitochondria, although trnH genes possess a GĀ1 tRNAHis guanylyltransferase activity is present in plant mitochondria |
| 2.7.7.79 | p-tRNAHis + ATP + GTP |
the G(-1) residue is both necessary and sufficient for aminoacylation of tRNA by histidyl-tRNA synthetase in vitro and is required for aminoacylation in vivo |
| 2.7.7.79 | p-tRNAHis + ATP + GTP + H2O |
- |
| 2.7.7.79 | p-tRNAHis + ATP + GTP + H2O |
overall reaction |
