Uracil DNA glycosylase family 2, includes thymine DNA glycosylase, mismatch-specific uracil DNA glycosylase and similar proteins
Uracil DNA glycosylase family 2 consists of thymine DNA glycosylase (TDG), which removes uracil and thymine from G:U and G:T mismatches in double-stranded DNA. It includes mismatch-specific uracil DNA glycosylase (MUG), the prokaryotic homolog of TDG. Escherichia coli MUG is highly specific to G:U mismatches but also repairs G:T mismatches at high enzyme concentration. Uracil-DNA glycosylases (UDGs) initiate repair of uracils in DNA. Uracil in DNA can arise as a result of misincorporation of dUMP residues by DNA polymerase or via deamination of cytosine. Uracil in DNA mispaired with guanine is one of the major pro-mutagenic events, causing G:C->A:T mutations. Thus, UDG is an essential enzyme for maintaining the integrity of genetic information. UDGs have been classified into various families on the basis of their substrate specificity, conserved motifs, and structural similarities. Although these families demonstrate different substrate specificities, often the function of one enzyme can be complemented by the other..
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