Interaction between Membrane Functions and Protein Synthesis in Reticulocytes: Specific Cleavage of 28‐S Ribosomal RNA by a Membrane Constituent

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Abstract
A factor isolated from rabbit reticulocyte white ghost by Triton X-100 treatment blocks protein synthesis at the elongation-termination stage. Factor-treated ribosomes were found to have an identical buoyant density to that of control ribosomes. When incubated with either reticulocyte ribosomes or rRNA, the factor products specific cuts in the 28-S rRNA component without damaging the 18-S RNA. Incubations of pancreatic or T1 RNase, with rRNA, at similar protein-synthesis inhibitory concentrations effected a complete breakdown to oligo- and mononucleotides. When challenged with isolated 28-S or 18-S reticulocyte rRNA, the highly purified factor only attacked the 28-S RNA species. There was no accumulation of nucleotides or oligonucleotides and the membrane factor causes inhibition of protein synthesis by having a specific endonucleolytic cleavage activity.