Editing Transfer RNA (section)

==Aminoacylation==
{{see also|Aminoacyl-tRNA}}
[[Aminoacylation]] is the process of adding an aminoacyl group to a compound. It covalently links an [[amino acid]] to the CCA 3′ end of a tRNA molecule.
Each tRNA is aminoacylated (or ''charged'') with a specific amino acid by an [[aminoacyl tRNA synthetase]]. There is normally a single aminoacyl tRNA synthetase for each amino acid, despite the fact that there can be more than one tRNA, and more than one anticodon for an amino acid. Recognition of the appropriate tRNA by the synthetases is not mediated solely by the anticodon, and the acceptor stem often plays a prominent role.<ref name="pmid7692438">{{cite journal | vauthors = Schimmel P, Giegé R, Moras D, Yokoyama S | title = An operational RNA code for amino acids and possible relationship to genetic code | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 90 | issue = 19 | pages = 8763–8768 | date = October 1993 | pmid = 7692438 | pmc = 47440 | doi = 10.1073/pnas.90.19.8763 | bibcode = 1993PNAS...90.8763S | doi-access = free }}</ref>
Reaction:
# amino acid + [[Adenosine triphosphate|ATP]] → aminoacyl-AMP + [[Pyrophosphate|PPi]]
# aminoacyl-AMP + tRNA → aminoacyl-tRNA + [[Adenosine monophosphate|AMP]]
Certain organisms can have one or more aminophosphate-tRNA synthetases missing. This leads to charging of the tRNA by a chemically related amino acid, and by use of an enzyme or enzymes, the tRNA is modified to be correctly charged. For example, ''[[Helicobacter pylori]]'' has glutaminyl tRNA synthetase missing. Thus, glutamate tRNA synthetase charges tRNA-glutamine(tRNA-Gln) with [[glutamate]]. An amidotransferase then converts the acid side chain of the glutamate to the amide, forming the correctly charged gln-tRNA-Gln.