After infection of mouse L cells with mengovirus, there is a rapid inhibition of protein synthesis, a concurrent disaggregation of polysomes, and an accumulation of 80S ribosomes. These 80S ribosomes could not be chased back into polysomes under an elongation block. The infected-cell 80S-ribosome fraction contained twice as much initiator methionyl-tRNA and mRNA as the analogous fraction from u...

The number of antibiotics active on eukaryotic ribosomes has been considerably increased in the last few years. Some of them are active only in eukaryotic ribosomes whereas some others are active on prokaryotic as well as eukaryotic ribosomes (Table 1). There is ample evidence suggesting a sirnilar mechanism for the elongation cycle by prokaryotic and eukaryotic ribosomes. This evidence is main...

On the basis of the recent atomic-resolution x-ray structure of the 50S ribosomal subunit, residues A2451 and G2447 of 23S rRNA were proposed to participate directly in ribosome-catalyzed peptide bond formation. We have examined the peptidyltransferase and protein synthesis activities of ribosomes carrying mutations at these nucleotides. In Escherichia coli, pure mutant ribosome populations car...

Two distinct heat labile factors (I and II) were found to be required for the in vitro synthesis of polyphenylalanine by rice ribosomes (Oryza sativa var. Bluebonnct) and polyuridylic acid. These factors were present in both the crude supernatant and on crude ribosomes. Factor I was removed from the crude ribosomes by [ill] (0.6%), while factor II was eliminated from deoxycholate washed ribosom...

The relative ability of 44 erythromycin analogues to bind to ribosomes was determined by their effect on ['4C]erythromycin binding to Escherichia coli ribosomes. The association and dissociation constants of each of these erythromycin derivatives were determined as well as their interaction coefficient for their binding to ribosomes. Substitutions were made on various portions of the erythromyc...

In eukaryotes, Dom34 is involved in the rescue of ribosomes that stall on mRNAs during protein synthesis. Using ribosome profiling, Guydosh and Green reveal that, in addition to rescue of ribosomes stalled on truncated mRNAs, Dom34 also recycles ribosomes that are unexpectedly found in the 3' untranslated regions of many cellular mRNAs.

I . Nascent translation products on mitochondrial ribosomes were selectively labeled in vivo in the presence of cycloheximide with radioactive leucine. They were isolated together with the ribosomes. 2. The labeled polypeptides show a high tendency to aggregate and can only be kept in solution in the presence of detergents such as dodecylsulfate. Also, mitochondrial ribosomes carrying nascent p...

Ribosome recycling factor (RRF), elongation factor-G (EF-G), and ribosomes from Thermus thermophilus (tt-) and Escherichia coli (ec-) were used to study the disassembly mechanism of post-termination ribosomal complexes by these factors. With tt-RRF, ec-EF-G can release bound-tRNA from ec-model post-termination complexes. However, tt-RRF is not released by ec-EF-G from ec-ribosomes. This complex...

Antibiotics were used as probes of ribosome topology and function. Studies of [(14)C]chloramphenicol and [(14)C]erythromycin binding to ribosomes and polyribosomes revealed the following features. The requirement of high K(+) concentration (150 mM) for [(14)C]chloramphenicol binding to NH(4)Cl-washed ribosomes resulted from the washing procedure. Neither native 70S ribosomes nor polyribosomes r...

Radioactive amino acids were incorporated in vivo into Neurospora crassa cells, and the mitochondrial ribosomes were isolated. The incorporat,ion of radioactivity into the proteins of these ribosomes was inhibited by cycloheximide, but not by chloramphenicol. It is therefore concluded that these proteins are synthesized on the cycloheximide sensitive and chloramphenicol insensitive cytoplasmic ...