http://www.jbc.org/content/251/6/1799.full.pdf

The ribosomal proteins of Saccharomyces cerevisiae. Phosphorylated and exchangeable proteins.

Screening of the complete genome sequence from the yeast Saccharomyces cerevisiae has enabled us to compile a complete list of the genes encoding cytoplasmic ribosomal proteins in this organism.



Putative ribosomal protein genes were selected primarily on the basis of the sequence similarity of their products with ribosomal proteins from other eukaryotic organisms, in particular the rat. These genes were subsequently screened for typical yeast rp-gene characteristics, viz. (1) a high codon adaptation index; (2) their promoter structure and (3) their responses to changes in growth conditions.



The yeast genome appears to carry 78 different genes, of which 59 are duplicated, encoding 32 different small-subunit and 46 large-subunit proteins. A new nomenclature for these ribosomal proteins is proposed. © 1998 John Wiley & Sons, Ltd.

The list of cytoplasmic ribosomal proteins of Saccharomyces cerevisiae

Translation of mRNA into protein is a fundamental step in eukaryotic gene expression requiring the large (60S) and small (40S) ribosome subunits and associated proteins. By modern proteomic approaches, we previously identified a novel 40S-associated protein named Asc1p in budding yeast and RACK1 in mammals. The goals of this study were to establish Asc1p or RACK1 as a core conserved eukaryotic ribosomal protein and to determine the role of Asc1p or RACK1 in translational control. We provide biochemical, evolutionary, genetic, and functional evidence showing that Asc1p or RACK1 is indeed a conserved core component of the eukaryotic ribosome. We also show that purified Asc1p-deficient ribosomes have increased translational activity compared to that of wild-type yeast ribosomes. Further, we demonstrate that asc1Δ null strains have increased levels of specific proteins in vivo and that this molecular phenotype is complemented by either Asc1p or RACK1. Our data suggest that one of Asc1p's or RACK1's functions is to repress gene expression.

Yeast Asc1p and mammalian RACK1 are functionally orthologous core 40S ribosomal proteins that repress gene expression.

The course of the assembly of ribosomal subunits in yeast

Yeast use translational control to compensate for extra copies of a ribosomal protein gene

The number of proteins in yeast ribosomal subunits was determined by two-dimensional polyacrylamide gel electrophoresis. The 40S subunit obtained after dissociation of ribosomes at high ionic strength contains 30 different protein species (including six acidic proteins). The 60S subunit, obtained in the same way contains 39 different species (including 1 acidic protein). While the total number of protein species found in yeast ribosomes, thus, is in close agreement with those reported for other eukaryotic organisms, the distribution between acidic and basic proteins is quite different.

T. Kruiswijk

Papers

Analysis of the protein composition of yeast ribosomal subunits by two-dimensional polyacrylamide gel electrophoresis.