Incorporation of nucleotides into DNA by mammalian DNA polymerase in the presence of a single deoxynucleoside triphosphate.

Rat ascites hepatoma cell DNA polymerases (EC 2.7.7.7), especially low molecular weight polymerase, could incorporate a significant amount of single nucleotide into acid-soluble products in the absence of the other three deoxynucleoside triphosphates when activated DNA was used as a template. This relaxed requirement for deoxynucleotides was not observed when poly[d(A-T).d(T-A)] was used as a template. Nearest-neighbour base analyses of the products formed in the presence of a single deoxynuclesode triphosphate revealed that the reaction is not of a terminal transferase-type but a very limited repair synthesis in which one or a few triphosphates are incorporated at numerous 3'-hydroxyl ends.