Late steps in the maturation of Drosophila 26 S ribosomal RNA: generation of 5-8 S and 2 S RNAs by cleavages occurring in the cytoplasm.

Abstract Mature Drosophila 26 S ribosomal RNA contains a central hidden break and is hydrogen-bonded to two small RNA species, a 5.8 S RNA molecule similar to that found in other eukaryotic cells and a smaller, 2 S RNA species. The sequence of this 2 S RNA molecule has been determined; investigation of its biosynthesis and of concomitant changes in the 26 S RNA molecule show that after transcription and processing to 26 S size the large rRNA molecule is first submitted to a central cleavage in the nucleus; it is then transported to the cytoplasm where further maturation cleavages generate simultaneously 5.8 S and 2 S RNAs.