Ribosomal subunits were prepared from fungal spore ribosomes and reassociated to yield biologically active ribosomes.

this study was conducted to investigate the effects of doses of 25, 50 and 75 kgy of gamma ray (gr) and electron beam (eb) ionizing radiations on ruminal disappearance of amino acids (aas) and protein subunits of canola meal (cm). the nylon bag technique was used for degradability trial. three ruminally fistulated taleshi bulls were used for this aim. the disappearance trends of protein subunit...

Macromolecular protein complexes catalyze essential physiological processes that sustain life. Various interactions between subunits could increase the effective mass of certain peptide groups, thereby compartmentalizing $\alpha$-helices. Here, we study differential effects applied massive barriers upon soliton-assisted energy transport within proteins. We demonstrate excentric barriers, locali...

Interactions between tRNA or its analogs and 23S rRNA in the large ribosomal subunit were analyzed by RNA footprinting and by modification-interference selection. In the E site, tRNA protected bases G2112, A2392, and C2394 of 23S rRNA. Truncated tRNA, lacking the anticodon stem-loop, protected A2392 and C2394, but not G2112, and tRNA derivatives with a shortened 3' end protected only G2112, but...

The eukaryotic class 1 polypeptide chain release factor is a three-domain protein involved in the termination of translation, the final stage of polypeptide biosynthesis. In attempts to understand the roles of the middle domain of the eukaryotic class 1 polypeptide chain release factor in the transduction of the termination signal from the small to the large ribosomal subunit and in peptidyl-tR...

The sarcin-ricin loop (SRL) of 23S rRNA in the large ribosomal subunit is a factor-binding site that is essential for GTP-catalyzed steps in translation, but its precise functional role is thus far unknown. Here, we replaced the 15-nucleotide SRL with a GAAA tetraloop and affinity purified the mutant 50S subunits for functional and structural analysis in vitro. The SRL deletion caused defects i...

Newly synthesized proteins leave the ribosome through a narrow tunnel in the large subunit. During ongoing synthesis, nascent protein chains are particularly sensitive to aggregation and degradation because they emerge from the ribosome in an unfolded state. In bacteria, the first protein to interact with nascent chains and facilitate their folding is the ribosome-associated chaperone trigger f...

A minimum cycle basis of the tertiary structure of a large ribosomal subunit (LSU) X-ray crystal structure was analyzed. Most cycles are small, as they are composed of 3- to 5 nt, and repeated across the LSU tertiary structure. We used hierarchical clustering to quantify and classify the 4 nt cycles. One class is defined by the GNRA tetraloop motif. The inspection of the GNRA class revealed pec...

Determining the mechanism by which tRNAs rapidly and precisely transit through the ribosomal A, P, and E sites during translation remains a major goal in the study of protein synthesis. Here, we report the real-time dynamics of the L1 stalk, a structural element of the large ribosomal subunit that is implicated in directing tRNA movements during translation. Within pretranslocation ribosomal co...

The M and S components of virginiamycin (VM and VS) inhibit protein synthesis in bacteria--reversibly when a single component is present and irreversibly when both are present. In cell-free systems, each factor binds to the large ribosomal subunit, and the affinity of ribosomes for VS is enhanced in the presence of VM. The present work shows that the action of VM (a 500-dalton modified depsipep...