title: Inhibition of cell-free protein synthesis by low-molecular-weight nuclear polyadenylate-containing ribonucleic acid species isolated from the lactating guinea pig.
abstract: 1. Poly(A)-containing RNA was isolated from the nuclei of mammary gland, liver and brain of lactating guinea pigs. 2. Total nuclear poly(A)-containing RNA from mammary gland inhibited mRNA-directed protein synthesis by a wheat-germ cell-free system. It also inhibited the endogenous activity of the wheat-germ and other cell-free systems. It did not inhibit a wheat-germ cell-free system directed by poly(U). 3. Total nuclear poly(A)-containing RNA from liver and brain did not inhibit the mRNA-directed wheat-germ system. 4. Fractionation of the nuclear poly(A)-containing RNA revealed inhibitory activity in the less than 10 S fraction from mammary gland as well as that from liver and brain. 5. The mechanism of protein-synthesis inhibition appeared to be at the level of elongation. 6. The inhibitory activity could be reversed in a wheat-germ system by increasing the amount of S-30 supernatant. 7. The mechanism of inhibition of protein synthesis is discussed in relation to other RNA species known to inhibit such systems.
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D002467:Cell Nucleus / Q000032:analysis; D002474:Cell-Free System / Q000187:drug effects; D002499:Centrifugation, Density Gradient; D003864:Depression, Chemical; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007774:Lactation; D008099:Liver / Q000032:analysis; D008321:Mammary Glands, Animal / Q000032:analysis; D008970:Molecular Weight; D011061:Poly A / Q000302:isolation & purification / Q000494:pharmacology*; D011247:Pregnancy; D014176:Protein Biosynthesis; D012313:RNA / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D011061:Poly A; D012313:RNA