Abstract
The 5' end of the rRNA precursor of D. discoideum was mapped on a cloned rDNA by S1 nuclease protection mapping, and the sequence of about 1240 nucleotides surrounding the transcriptional initiation site of the rRNA gene has been determined. Repeated sequences consisting of 16 nucleotides appeared in the region upstream from the initiation point. Comparison of the nucleotide sequences around the initiation site of rRNA genes in three lower eukaryotes, D. discoideum, Saccharomyces cerevisiae and Tetrahymena pyriformis, indicated that there was little similarity in the nontranscribed spacer regions, but in the transcribed spacer regions near the initiation point, very similar sequences consisting of 9 nucleotides were found.