Single Strand Selective Monofunctional Uracil DNA Glycosylase 1 (SMUG1)

SMUG1 is a glycosylase that removes uracil from single- and double-stranded DNA in nuclear chromatin, thus contributing to base excision repair. The deduced 270-amino acid protein has a calculated molecular mass of about 30 kD. Human SMUG1 shares 60% identity with the Xenopus protein. Fluorescence-tagged SMUG1 localized predominantly to the nucleus of transiently transfected HeLa cells.

SMUG1 showed broader substrate specificity than UNG2, and AP endonuclease had a strong stimulatory effect on SMUG1 against double-stranded uracil, apparently due to enhance dissociation of SMUG1 from AP sites in double-stranded DNA. SMUG1 accumulated within nucleoli in cultured epithelial cells, while UNG2 was excluded from nucleoli.