A novel factor for DNA-dependent RNA polymerase II in rat liver nuclei.

The author found, in rat liver nuclei, a novel factor which exhibited a strong inhibitory effect on RNA chain initiation by various classes of RNA polymerases (I, II and III) using an exogenous DNA template. The molecular weight of this factor was estimated to be 70 K daltons, and its activity was not affected by treatment with trypsin, RNase A, lipase C, alpha-amylase and heat. However, its activity was inactivated by a digestion of glycosidases. The molecule is shown to contain a considerable amount of sugars by physicochemical analysis. In addition, it is elucidated that the factor is not heparin which has a similar biological activity.