Figure 1

The under-translated transcripts of Saccharomyces cerevisiae. (a) Translational efficiency across the transcriptome. Translation state array data from exponentially growing yeast were used for 3916 transcripts with open reading frames (ORFs) longer than 400 nucleotides and whose distributions after sucrose gradient centrifugation could be modeled reliably [3]. To calculate translational efficiency, the fraction of each transcript in polysomes was multiplied by the mean ribosome density, expressed as ribosomes per 1,000 nucleotides of ORF, and these values were normalized to a mean of 1.0. Translational efficiencies are plotted on a logarithmic scale versus relative transcript level obtained from the array analysis [3]. (b) Ribosome loading on the transcriptome of steady-state growing yeast. Ribosome density (ribosomes per 1,000 nucleotides) is plotted against the fraction of each transcript in polysomes. The data are those used to calculate the translational efficiencies in (a). The under-translated transcripts (<0.25 of the mean translation efficiency) are represented by the filled symbols and the remaining transcripts by the open symbols. (c) Gene ontology (GO) analysis of the under-translated transcriptome. The frequency of biologic process catagories appearing in the indicated populations was analyzed, as described in the text, using the GO tools associated with the Saccharomyces Genome Database [66].