The amount of chloroplast ribosomal RNAs of Chlamydomonas reinhardtii which sediment at 15,000 g is increased when cells are treated with chloramphenicol. Preparations of chloroplast membranes from chloramphenicol-treated cells contain more chloroplast ribosomal RNAs than preparations from untreated cells. The membranes from treated cells also contain more ribosome-like particles, some of which...

We have compared the behavior of a prokaryotic mRNA in a eukaryotic ribosome binding system and of a eukaryotic mRNA in a prokaryotic ribosome binding system. Using (32)P- and (125)I-labeled bacteriophage f1 mRNA, we have shown that rabbit reticulocyte 80S ribosomes can protect specific sequences from pancreatic RNase digestion, including those sequences protected by Escherichia coli ribosomes....

The conversion of a ribosomal RNA transcript to a cytoplasmic ribosome requires hundreds of accessory RNA and protein factors. Two papers published recently in Molecular Cell provide first looks at the association of these processing factors with the intermediates in ribosome synthesis (Harnpicharnchai et al., 2001; Bassler et al., 2001).

1 describes the design, synthesis and operation of an artificial small-molecule capable of synthesizing peptides in a sequence-specific manner. The design of this artificial molecular machine was, in the author's own words, " inspired by the ribosome " ; 2 with several elements analogous to ribosomal protein synthesis (Fig. 1). The tRNA's of conventional translation are substituted by amino aci...

RNA polymerase doesn't make deliveries R esearchers are divided over whether RNA polymerase tracks down genes that are ready to be transcribed or whether the enzyme remains in place. Xu and Cook add to the evidence that a gene has to relocate to one of a few sites in the nucleus to be transcribed. One possibility is that the RNA polymerase, the DNA-reading enzyme, moves from gene to gene, trans...

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...