-!- Aprataxin is a DNA-binding protein that catalyzes (among other activities) the 3' decapping of DNA-ppG (formed by EC 6.5.1.8). -!- The enzyme binds the guanylate group to a histidine residue at its active site, forming a covalent enzyme-nucleotide phosphate intermediate, followed by the hydrolysis of the guanylate from the nucleic acid and its eventual release. -!- The enzyme also possesses the activity of EC 3.1.11.7 and EC 3.1.11.8.

-!- Aprataxin is a DNA-binding protein involved in different types of DNA break repair. -!- The enzyme acts (among other activities) on abortive DNA ligation intermediates that contain an adenylate covalently linked to the 5'-phosphate DNA terminus. -!- It also acts when the adenylate is covalently linked to the 5'-phosphate of a ribonucleotide linked to a DNA strand, which is the result of abortive ligase activty on products of EC 3.1.26.4, an enzyme that cleaves RNA-DNA hybrids on the 5' side of the ribonucleotide found in the 5'-RNA-DNA-3' junction. -!- Aprataxin binds the adenylate group to a histidine residue within the active site, followed by its hydrolysis from the nucleic acid and eventual release, leaving a 5'-phosphate terminus that can be efficiently rejoined. -!- The enzyme also possesses the activities of EC 3.1.11.8 and EC 3.1.12.2.