Polyamine concentration, activity of the ribosomal dissociation factor and proportion of ribosomes active in protein synthesis in the 4-dimethylaminoazobenzene-induced rat hepatoma

4-Dimethylaminoazobenzene (DAB) induced liver tumour tissue showed a reduced proportion of ribosomes active in protein synthesis compared with control liver. Tumour cell extracts caused an increased association of ribosome subunits into inactive 80 S monomers, compared with the dissociation into active subunits caused by normal liver extracts. These findings may be explained, at least in part, by the increased proportion of spermidine to putrescine found in tumour tissue which would predispose towards association of the subunits.