Transformant phages expressing L15, a yeast ribosomal protein which binds to 26S rRNA and interacts with the acidic ribosomal proteins, were isolated by screening a yeast cDNA expression library in lambda gt11 with specific monoclonal antibodies. Using yeast DNA HindIII fragments that hybridize with the cDNA insert from the L15-expressing clones, minilibraries were prepared in pUC18, which were afterward screened with the same cDNA probe. In this way, plasmids carrying two different types of genomic DNA inserts were obtained. The inserts were subcloned and sequenced and we found a similar coding sequence in both cases flanked by 5' and 3' regions with very low homology. Sequences homologous to the consensus TUF-binding UAS boxes are present in the 5' flanking regions of both genes. Southern analysis revealed the presence of two copies of the L15 gene in the Saccharomyces cerevisiae genome, which are located in different chromosomes. The encoded amino acid sequence corresponds, as expected, to protein L15 and shows a high similarity to bacterial ribosomal protein L11.