Structure of a ribosomal protein gene in Mucor racemosus.

As an extension of our analysis of the translational apparatus of Mucor racemosus we have isolated a gene encoding a ribosomal protein of Mucor. Based on a method developed for S. cerevisiae, we identified by hybrid selection and in vitro translation a lambda-Charon 4A clone containing the genomic copy of a Mucor ribosomal protein. The gene consisted of two exons of 57 and 387 nucleotides. The two exons were separated by an 131 nucleotide intron. The processed transcript was 714 nucleotides in length and contained a 25 nucleotide untranscribed leader and an 114 nucleotide untranscribed 3'-end. The protein predicted from the nucleotide sequence contained 148 amino acids and exhibited 61% identity with the S19 ribosomal protein of Xenopus laevis. The promoter region of the gene contained sequences highly homologous to the RPG and Homol1 promoter elements found in S. cerevisiae. Southern blot analysis indicated that the Mucor genome contains three copies of this gene.