title: Inhibition of cell-free protein synthesis by low-molecular-weight RNAs from free cytoplasmic ribonucleoprotein particles.
abstract: Free cytoplasmic messenger ribonucleoprotein (mRNP) particles from rat liver were treated with EDTA and separated into two populations of RNP particles with sedimentation maxima of 20 S and 35 S respectively. The 20-S and 35-S RNP particles, treated with 0.5 M KCl, have protein-to-RNA ratios of 0.31:1 and 5.7:1 respectively. Whereas 20-S and 35-S RNP particles exhibit a similar protein complement of seven major polypeptides, the low-molecular-weight RNA components of the two particle populations are different. A characteristic set of distinct low-molecular-weight RNAs is found for 20-S and 35-S RNP particles. When the individual low-molecular-weight RNAs of 20-S and 35-S RNP particles isolated from preparative polyacrylamide gels were assayed for their capability to inhibit protein synthesis in vitro, several potent translational inhibitory RNAs were detected. In particular, the low-molecular-weight RNAs of 147, 203 and 263 nucleotides in length associated with the 35-S RNP particles turned out to be strong inhibitors of protein synthesis.
mesh_terms: D000818:Animals; D002474:Cell-Free System; D003593:Cytoplasm / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008970:Molecular Weight; D009698:Nucleoproteins / Q000378:metabolism*; D014176:Protein Biosynthesis; D012313:RNA / Q000502:physiology*; D051381:Rats; D012261:Ribonucleoproteins / Q000378:metabolism*
chemical_list: D009698:Nucleoproteins; D012261:Ribonucleoproteins; D012313:RNA