11 Protein Synthesis and Translational Control in Saccharomyces cerevisiae

Abstract

I. INTRODUCTION The process of translation in Saccharomyces cerevisiae does not appear to differ fundamentally from the way it occurs in other organisms. Thus, much of what follows represents a comparison of the components and reactions of the protein synthetic machinery in yeast with their counterparts in other organisms, both prokaryotic and eukaryotic. For example, aminoacylation of tRNA and polypeptide chain elongation appear to be very similar in yeast and Escherichia coli, and, although the mechanism of translation initiation in Saccharomyces differs importantly from that described for bacteria, it closely resembles the process elucidated for plants and animals. Despite these similarities with other well-studied systems, the powerful genetic techniques developed for Saccharomyces make it very worthwhile to study protein synthesis in this organism. As described below, the genes encoding many components of the translational apparatus have been isolated from yeast and are being manipulated with genetic techniques to learn the complete functions of their gene products in vivo. This enterprise is particularly important for the reactions involved in translation initiation for which many differences exist between eukaryotes and prokaryotes. Mutational analysis of yeast should indicate whether the large number of proteins implicated in the process of initiation in eukaryotes from biochemical studies of in vitro systems is actually required for translation in vivo. This approach is extremely difficult for the multicellular organisms used most frequently to study eukaryotic protein synthesis. In addition, the isolation of mutations that alter the efficiency or fidelity of protein synthesis in yeast is likely to...