E. coli Mismatch Uracil DNA Glycosylase (Mug protein) is an 18 kDa constitutively expressed protein which belongs to the TDG/mug DNA glycosylase family. It has been proposed that the Mug protein excises 3,N4-ethenocytosine and removes the uracil base from mismatches in the order of U:G>U:A, although the biological role remains unclear. Uracil bases in DNA can arise from deamination of cytosine giving rise to increased spontaneous mutations. The enzyme Uracil-N-Glycosylase removes uracil from the DNA leaving an AP site. It is capable of hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of the DNA and the mispaired base. The complementary strand guanine functions in substrate recognition. It is required for DNA damage lesion repair in stationary-phase cells.Alternative Names: G/U Mismatch-Specific DNA Glycosylase, Double-Strand-Specific Uracil Glycosylase, Mismatch-Specific Uracil DNA-Glycosylase, MUG, mug, ygjF