Dephosphorylates specifically the 5' and 2'(3')-phosphates of uracil and thymine deoxyribonucleotides, and so protects mitochondrial DNA replication from excess dTTP. Has only marginal activity towards dIMP and dGMP.
Subcellular locations: Mitochondrion
Highly expressed in heart, brain and skeletal muscle. Detected at very low levels in kidney and pancreas.