Precursors of ribosomal RNA in the cellular slime mold Dictyostelium discoideum. Isolation and characterization.

The pathway of ribosomal RNA biogenesis in Dictyostelium discoideum has been defined through identification, isolation, and characterization of the rapidly labeled nuclear RNAs which are intermediates in the process. Comparison of the methylation patterns, base compositions, two-dimensional oligonucleotide maps, and hybridization properties of these intermediate RNAs with those of mature rRNAs has established clearly the precursor-product sequence relationships supporting the following scheme for rRNA production and processing: (formula: see text) The relationship of the 37 S RNA of Dictyostelium to primary rRNA transcripts of prokaryotes and other eukaryotes is discussed.