2'-Deoxyguanosine 5'-monophosphate (dGMP) is used as a substrate of guanylate kinases to generate dGDP, which in turn is phosphorylated to dGTP, a nucleotide precursor used in DNA synthesis. In addition, dGMP can be efficiently phosphorylated by the type I thymidylate kinase of the malarial agent P. falciparum. In humans, deficiency of mitochondrial deoxyguanosine kinase, which synthesizes dGMP from ATP and deoxyguanosine, contributes to mitochondrial DNA depletion syndrome.