A mixture of cytoplasmic (80S) and chloroplast (70S) ribosomes from Chlamydomonas reinhardtii was freed of contaminating membranes by sedimentation of the postmitochondrial supernatant through a layer of 1.87 M sucrose. The purified ribosomes were separated into 80S and 70S fractions by centrifugation at a relatively low speed on a 10-40% sucrose gradient containing 25 mM KCl and 5 mM MgCl(2). ...

A class of 80 S ribosomes has been isolated from purified yeast mitochondria. These ribosomes are distinguished from cytoplasmic ribosomes of the postmitochondrial supernatant fraction by having a greater stability against the dissociating effect of 0.4 M KCI. These results confirm observations of Schmitt ((1969) Fed. Eur. Biochem. Sot. Left. 4, 234-238). Ribosome dissociability has been examin...

We have developed a novel chromatography for the rapid isolation of active ribosomes from bacteria without the use of harsh conditions or lengthy procedures that damage ribosomes. Ribosomes interact with an alkyl linker attached to the resin, apparently through their RNA component. Examples are given with ribosomes from Escherichia coli, Deinococcus radiodurans, and with clinical isolates of St...

An average of 17% of rabbit reticulocyte ribosomes are closely bound to the cell membrane. Evidence is presented to indicate that membrane binding of reticulocyte ribosomes is not an artifact. Membrane-bound reticulocyte ribosomes differ in physical and chemical properties from free reticulocyte ribosomes in having a high coefficient of sedimentation (greater than 400 S) and a high protein to R...

To determine the region of 16S ribonucleic acid (RNA) at the interface between 30 and 50S ribosomes of Escherichia coli, 30 and 70S ribosomes were treated with T1 ribonuclease (RNase). The accessibility of 16S RNA in the 5' half of the molecule is the same in 30 and 70S ribosomes. The interaction with 50S ribosomes decreases the sensitivity to T1 RNase of an area in the middle of 16S RNA. A lar...

Ribosomes from muscle of diabetic rats synthesized less polyphenylalanine than normal ribosomes at low magnesium concentrations (5 to 10 mM), but they were more active than normal ribosomes at high magnesium concentrations (12.5 to 20 mM). The magnesium dependence of binding of phenylalanyl transfer RNA to normal and diabetic ribosomes closely paralleled the synthesis of polyphenylalanine. A po...

Synthetic biology constructs often rely upon the introduction of “circuit” genes into host cells, in order to express novel proteins and thus endow with a desired behavior. The expression these new “consumes” existing resources cell, such as ATP, RNA polymerase, amino acids, ribosomes. Ribosomal competition among strands mRNA may be described by system nonlinear ODEs called Flow Model (RFM). fo...

Abstract By interacting with the mRNA 5′ cap, translation initiation factor eIF4E plays a critical role in selecting mRNAs for protein synthesis eukaryotic cells. Caf20 is member of family proteins found across eukaryotes termed 4E-BPs, which compete eIF4G interaction eIF4E. independently interacts ribosomes. Thus, modulates selection process via poorly understood mechanisms. Here we performed ...

We have determined the number of proteins in rat skeletal muscle 80 S ribosomes and ribosomal subparticles by twodimensional polyacrylamide gel electrophoresis. The proteins were compared with those from liver ribosomes. The small subunit of muscle ribosomes contained 31 proteins: it had two proteins (SJ and S,,,2) which were not found in liver 40 S particles; one protein (S31*) was always foun...

Isolation of biologically active cell components from multicellular eukaryotic organisms often poses difficult challenges such as low yields and inability to retain the integrity and functionality of the purified compound. We previously identified a cap-independent translation enhancer (3'CITE) in the 3'UTR of Turnip crinkle virus (TCV) that structurally mimics a tRNA and binds to yeast 80S rib...