Upon fertilization of Paracentrotus lividus eggs, the ability of their ribosomes to form a ternary complex with poly(U) and phenylalanyl-tRNA is enhanced. In addition, it is possible to extract from ribosomes of the unfertilized egg a protein factor that inhibits polyphenylalanine synthesis by decreasing the binding of mRNA and aminoacyl-tRNA to the ribosomes. The observed increase in the rate ...

Ribosomes synthesizing secretory and membrane proteins are bound to the endoplasmic reticulum (ER) membrane and attach to ribosome-associated membrane proteins such as the Sec61 complex, which forms the protein-conducting channel in the membrane. The ER membrane-resident Hsp40 protein ERj1 was characterized as being able to recruit BiP to ribosomes in solution and to regulate protein synthesis ...

Santer, Melvin (Haverford College, Haverford, Pa.), and Josephine R. Smith. Ribonuclease sensitivity of Escherichia coli ribosomes. J. Bacteriol. 92:1099-1110. 1966.-The ribonucleic acid (RNA) contained in 70S ribosomes and in 50S and 30S subunits was hydrolyzed by pancreatic ribonuclease. A 7% amount of the RNA was removed from the 70S particle; at 10(-4)m magnesium concentration, a maximum of...

Ribosomes that are synthesizing polypeptides in vitro on certain natural and synthetic messages are more susceptible to inactivation by colicin E3 than ribosomes treated with E3 in the absence of added message. The initiation step of protein synthesis appears to be sufficient to cause the conversion of ribosomes to a state more sensitive to colicin E3. Message and protein synthesis are not, how...

Proteomics of chloroplast ribosomes in spinach and Chlamydomonas revealed unique protein composition and structures of plastid ribosomes. These studies have suggested the presence of some ribosomal proteins unique to plastid ribosomes which may be involved in plastid-unique translation regulation. Considering the strong background of genetic analysis and molecular biology in Arabidopsis, the in...

Polysome formation in the embryos of Pinus thunbergii seeds was studied. Free ribosomes were dissociated to smaller subunits in a high salt buffer, but the complex ribosomes were not. The free ribosomes could be distinguished from monomer ribosomes derived from polysomes after RNase treatment. The monomer ribosomes present in the embryos of the dark-imbibed seeds were predominantly free ribosom...

The chemical-carcinogen-induced detachment of ribosomes from rat liver endoplasmic reticulum was studied in vitro. Incubation of postmitochondrial supernatant with 0.2 mM-diethylnitrosamine or N-2-acetylaminofluorene removed approx. 16% of membrane-bound ribosomes, measured as differences in RNA/protein values of membrane separated from unbound ribosomes by flotation. These ribosomes are also d...