Some properties of cytoplasmic RNA fractions of the mouse Ehrlich ascites carcinoma

Abstract

Two RNA subfractions from mouse Ehrlich ascites carcinoma 105 000 × g supernatant and three RNA subfractions from the tumor microsomal fraction have been resolved by chromatography on methylated albumin–kieselguhr. The five subfractions have been examined for their amino acid acceptor capacities and nucleotide compositions and by sucrose density-gradient centrifugation. One of the 105 000 × g supernatant fractions has been identified as amino acid acceptor or transfer RNA (tRNA) and the three microsomal components have been identified as tRNA, 5S RNA, and ribosomal RNA. The microsomal tRNA and 5S RNA appear to be associated with ribosomal RNA in a molar ratio approaching 2:1 and together make up about 6–8% of the total microsomal RNA. The second 105 000 × g supernatant RNA fraction has not been identified. It is recovered in widely varying amounts and behaves like heterogeneous material in chromatographic and sedimentation procedures.