Precursors of ribosomal RNA in yeast nucleus : Biosynthesis and relation to cytoplasmic ribosomal RNA

Abstract

In vivo methylated precursors of ribosomal RNA in yeast have been characterized on acrylamide gels. The initial ribosomal precursor in the yeast nucleus is a 37S RNA component, which is processed to a nuclear 28S RNA. Both the 37S and the 28S RNA components are important constituents of the yeast nucleus. A possible 33S RNA intermediate has been observed. Newly formed 18S rRNA rapidly enters the cytoplasm, while newly formed 26S rRNA appears later. The 26S rRNA is most probably formed from the nuclear 28S RNA.