The Dissociation of Rabbit Reticulocyte Ribosomes into Subparticles Active in Protein Synthesis

Abstract

Monoribosomes obtained from rabbit reticulocytes which had been pre‐incubated with sodium fluride in order to convert polysomes into monoribosomes were dissociated into ribosomal subparticles by treatment with 0.2 M KCl in the absence of magnesium. The subparticles were separated by centrifugation in sucrose gradients containing appropriate salt concentrations which neither promote the dissociation of ribosomes nor facilitate the association of subparticles. The unfractionated subparticle mixture was fully active in synthesizing polyphenylalanine when polyuridylic acid was added as messenger. Fractionated subparticles were, however, inactive in the cell‐free system even when polyamines, sulphydryl compounds or the post‐ribosomal fraction from ribosomes treated with 0.2 M KCl were added to the gradient. Copyright © 1969, Wiley Blackwell. All rights reserved