The Properties of 7-Methylguanine-containing Templates for Ribonucleic Acid Polymerase

Polyribonucleotides that contain 7-methylguanylic acid have been prepared and used to determine the base-pairing properties of 7-methylguanine in templates for RNA polymerase. Experiments with copolymers of uridylic and 7-methylguanylic acids indicate that 7-methylguanine can still pair normally with cytosine to produce copolymers of adenylic and cytidylic acids. When copolymers of cytidylic and 7-methylguanylic acids are incubated with GTP and UTP, some abnormal base pairing is evident between 7-methylguanine and uracil. However, this is at the same level as abnormal pairing between guanine and uracil, and can be blocked by the addition of CTP to the incubation mixture. It is concluded that the base-pairing properties of 7-methylguanine and guanine are very similar in this assay system.