Properties of RNA Polymerases from B16 Melanoma

Abstract

Some of the properties of RNA polymerases from melanotic and amelanotic B16 melanomas have been studied. Chromatin-bound RNA polymerase is activated by Mg ++ more the Mn ++ . Addition of ammonium sulfate was found to activate the enzyme. Preincubation with phospholipase A or phospholipase C as well as extraction with ether or iso-octane decreased the RNA polymerase activity in the presence of Mg ++ but not that in the presence of Mn ++ . The polymerase activity in the presence of high salt concentration (ammonium sulfate) was not affected by the phospholipases or by solvent extraction. Preincubation in the presence of trypsin was found to activate enzymatic activity in the presence of Mn ++ to a greater extent than in the presence of Mg ++ . RNA polymerase activity of melanoma mitochondria was decreased by treatment with phospholopase A or phosholopase C as well as by extraction with ether or iso-octane. Phospholipase D as well as wheat-germ lipase did not have any effect on the RNA polymerase activities of nuclei or mitochondria. α-amanitin was found to inhibit the nuclear RNA polymerase activity in the presence of Mn ++ at high salt concentration but not in the presence of Mg ++ . The RNA polymerase activity of melanoma mitochondria was not inhibited by alpha;-amanitin. The RNA polymerase activity in melanoma nuclei and mitochondria was inhibited by actinomycin D but rifamycin and rifampicin did not have any inhibitory action. Of the various tissues studied, the properties of the RNA polymerase from melanoma closely resembled those of the RNA polymerases from liver.