DUT is a member of the dUTPase family, which is known for catalyzing the pyrophosphoralysis of dUTP into dUMP and inorganic pyrophosphate. This function contributes to DNA replication and repair via de novo thymidylate biosynthesis, as the dUMP product is methylated by thymidylate synthase (TS) to form dTMP, which is then phosphorylated to dTTP. DUT is also crucial for maintaining genome integrity by reducing cellular dUTP levels, thereby preventing the repeated cycles of uracil misincorporation into DNA and DNA repair-mediated strand breaks that would lead to cell death. In addition to their different localizations, the two DUT isoforms display different expression patterns: while DUT-M is constitutively expressed, DUT-N is under cell cycle control and notably upregulated during S phase. These expression patterns correspond with their roles in the DNA replication cycle of their respective genomes, and thus indicate different regulatory mechanisms affecting each isoform.