Nucleotidyltransferases are transferase enzymes of phosphorus-containing groups, e.g., substituents of nucleotidylic acids or simply nucleoside monophosphates. The general reaction of transferring a nucleoside monophosphate moiety from A to B, can be written as:
A-P-N + B A + B-P-N
For example, in the case of polymerases, A is pyrophosphate and B is the nascent polynucleotide. They are classified under EC number 2.7.7 and they can be categorised into:
Nucleotidyl transferase is a component of the repair pathway for single nucleotide base excision repair. This repair mechanism begins when a single nucleotide is recognized by DNA glycosylase as incorrectly matched or has been mutated in some way (UV light, chemical mutagen, etc.), and is removed. Later, a nucleotidyl tranferase is used to fill in the gap with the correct base, using the template strand as the reference.