CHARACTERIZATION OF SACCHAROMYCES-CEREVISIAE GENES ENCODING RIBOSOMAL-PROTEIN YL6

We have characterised a Saccharomyces cerevisiae cDNA (cDNA13), origin ally isolated on the basis of the short half-life of the corresponding mRNA. We show here that its sequence is closely related to that of th e genes encoding ribosomal proteins K37, KD4 and K5 of Schizosaccharom yces pombe. 'mRNA13' also behaves like other mRNAs encoding ribosomal proteins, in that its abundance increases sharply when glucose is adde d to cells grown on ethanol (nutrient-upshift), and declines when cell s are subjected to a mild heat-shock. Unspliced mRNA13 accumulates whe n cells bearing a temperature-sensitive splicing mutation are grown at the restrictive temperature. The gene(s) corresponding to cDNA13, lik e other ribosomal protein genes of S. cerevisiae, thus contain an intr on. Southern blot analysis indicates the presence of two separate loci related to cDNA13 in the S. cerevisiae genome. From the sequence of o ne of these, a complete polypeptide sequence was deduced. The first 40 amino acids are identical to those of YL6, a S. cerevisiae ribosomal protein characterised only by N-terminal protein sequence analysis. Th ere is clear evidence within the genomic sequence for the predicted in tron, and for elements similar to those that regulate expression of ot her S. cerevisiae ribosomal protein genes.