More than 70 different proteins form two subunits of eukaryotic ribosomes and are major components of the total cellular protein. It has been reported that in various living organisms the biosynthesis of the different ribosomal proteins is regulated coordinately (Mager, 1988). Although some information concerning the primary structure of plant ribosoma1 proteins is available by isolating cDNA c...

Inherently disparate cell growth and division, which are intimately coupled through a delicate network of intracellular and extracellular signaling, require ribosomal biogenesis. A number of events imparting instability to ribosomal biogenesis can cause nucleolar stress. In response to this stress, several ribosomal proteins bind to MDM2 and block MDM2-mediated p53 ubiquitination and degradatio...

During the assembly process of ribosomal subunits, their structural components, the ribosomal RNAs (rRNAs) and the ribosomal proteins (r-proteins) have to join together in a highly dynamic and defined manner to enable the efficient formation of functional ribosomes. In this work, the assembly of large ribosomal subunit (LSU) r-proteins from the eukaryote S. cerevisiae was systematically investi...

We report the identification and molecular characterization of a novel nucleolar protein of rat liver. As shown by eoimmunoprecipitation this protein is associated with a previously identified nucleolar protein, Noppl40, in an apparently stoichiometric complex and has therefore been termed NAP57 (Noppl40-associated protein of 57 kD). Immunofluorescence and immunogold electron microscopy with NA...

The synthesis of cytoplasmic eukaryotic ribosomes is an extraordinarily energy-demanding cellular activity that occurs progressively from the nucleolus to the cytoplasm. In the nucleolus, precursor rRNAs associate with a myriad of trans-acting factors and some ribosomal proteins to form pre-ribosomal particles. These factors include snoRNPs, nucleases, ATPases, GTPases, RNA helicases, and a vas...

RPs (ribosomal proteins) are main components of the ribosome having essential functions in its biogenesis, function and structural integrity. Although most of the RP molecules are in the cytoplasm, being incorporated into translating ribosomes, some RPs have non-ribosomal functions when they are off ribosomal subunits. Notably, in eukaryotes, RPs are also present at transcription sites and some...

We have developed a method of r the direct measurement, in eukaryotic cells, of the synthesis of ribosomal proteins, irrespective of the synthesis of ribosomes. In this way the synthesis of ribosomal proteins has been examined in mutant strains of Saccharomyces cerevisiae, which are unable to synthesize ribosomes under nonpermissive conditions. The results suggest that the synthesis of more tha...

Two-dimensional polyacrylamide-gel electrophoretic analysis of yeast ribosomal proteins uniformly labelled in vivo with [methyl-3H]methionine and [1-'4C]methionine revealed that four ribosomal proteins are methylated, i.e. proteins S31, S32, L15 and L41. Lysine and arginine appear to be the predominant acceptors of the methyl groups. The degree of methylation ranges from 0.09 to 0.20 methyl gro...

The physiological importance of translational regulation in controlling the synthesis of ribosomal proteins from the L11 ribosomal protein operon was determined for the classical regulatory phenomena of growth rate dependence and stringent control. Translational regulation of the L11 operon by ribosomal protein L1, the L11 operon-specific translational repressor protein, was abolished by introd...