Polysomal RNA's of Rat Liver: Identification and Characterization of Several Kinds of High Molecular Weight RNA Other than 18S and 28S Species

Abstract

RNA was extracted from polysomes of rat liver by SDS-phenol method in the presence of bentonite and analyzed by polyacrylamide gel electrophoresis. When the gel concentration of 3.1% was used, four minor peaks were detected between the peaks of 28S and 18S RNA's. These RNA's were obtained from both free and membrane-bound polysomes. They were found to be associated with 60S ribosomal subunits. Upon treatment of polysomes with a low concentration of pancreatic RNase [EC 2.7.7.16], no degradation of these RNA's was observed. These results suggest that they are not messenger-type RNA's but structural RNA's in larger ribosomal subunits. The possible origin of these RNA's is discussed.