Comparison of the partial sequences of nucleolar and cytoplasmic RNA's of rat liver

Abstract

1. 1. The partial nucleotide sequences of nucleolar precursor RNA and cytoplasmic RNA were compared. 2. 2. The products of digestion of nucleolar and cytoplasmic RNA by pancreatic ribonuclease were analyzed by a two-step column chromatography procedure, in which oligonucleotides were first separated according to chain length, and then mono-, di- and trinucleotides were rechromatographed separately. 3. 3. In general, the base sequences of both nucleolar and cytoplasmic RNA deviated significantly from a random distribution. 4. 4. The distribution of 32P in the partial nucleotide sequences of nucleolar 45-S and 28-S RNA and cytoplasmic 28-S RNA differed only in minor details. 28-S rRNA seemed to have different base sequences from those of 18-S RNA. 5. 5. The nucleolar 45-S RNA chain cannot be converted as a whole to rRNA because there is a discrepancy between the frequencies of the partial nucleotide sequences of 45-S RNA and the sum of those of 28-S and 18-S rRNA. These results suggested that there are non-ribosomal sequences in nucleolar 45-S RNA of rat liver, as reported previously for tumor tissues 14,15.