The nucleotide composition of ribonucleic acids from subcellular components of yeast, Escherichia coli and rat liver, with special reference to the occurrence of pseudouridylic acid in soluble ribonucleic acid

Abstract

The analyses of the nucleotide composition of RNA's derived from various subcellular fractions of yeast and Escherichia coli B, revealed that the RNA found in the supernatant fraction has a unique nucleotide composition as compared with the RNA from the particle fractions. The supernatant RNA is characterized by the presence of a considerable amount of pseudouridylic acid and by higher cytidylic acid and lower adenylic and uridylic acid contents. Predominant localization of pseudouridylic acid in the RNA of the “pH 5 enzyme fraction” of rat liver was also observed. The relation between the ability to bind [ 14C]leucine and the content of pseudouridylic acid in RNA's prepared from large granules, small granules, and some subfractions of the 105,000 × g supernatant of yeast cells has also been investigated. The RNA prepared from the supernatant fraction is the only active RNA, those prepared from particle fractions failing to incorporate [ 14C]leucine. In five preparations of RNA derived from the acid-fractionated supernatant subfractions and the unfractionated supernatant, it was found that the ability to incorporate [ 14C]leucine into different RNA's is directly proportional to their pseudouridylic acid content. These data suggest that this nucleotide is characteristic of the RNA which incorporates amino acids (at least leucine).