STUDIES ON NUCLEAR 4 TO 7 S RNA OF NOVIKOFF HEPATOMA

Nuclei isolated from Novikoff ascites hepatoma cells by the citric acid procedure were found to be a useful source of nuclear 4 to 7 s RNA, i.e., approximately 9 mg were obtained per 100 g wet weight of cells. The 4 to 7 s RNA was separated into four main peaks by chromatography on Sephadex G100 columns and 11 or more components by polyacrylamide gel electrophoresis. Two uridylic acid-rich RNA fractions (approximately 5 to 7 s), which are found only in nuclei, were purified by preparative polyacrylamide gel electrophoresis; one was obtained in an electrophoretically homogeneous state and had a base composition of 22% adenine, 26% uracil, 33% guanine and 19% cytosine. The labeling patterns with either [14C]sodium formate or [methyl-14C]methionine as a precursor were different for the uridylic acid-rich nuclear RNA than for the 4 s and 5 s RNA. Evidence is presented that the uridylic acid-rich RNA of peak II is not a degradation product of high molecular weight RNA. © 1969.