Diversity and nature of ribosomal pools in hepatoma 7800 and host liver.

1. The ribosomal components in the postmitochondrial supernatant of a rat hepatoma (hepatoma 7800) and the corresponding host liver were examined for diversity and functional competence. 2. The ;free' and ;membrane-bound' polyribosomes of both tissues were equally active in vivo and had equilibrated with newly synthesized ribosomes 4hr. after administration of [6-(14)C]orotic acid. 3. The inactive monomer-dimer pool in hepatoma 7800 was unattached to membranes and a larger fraction of the polyribosomes was free in hepatoma than in liver. 4. By using sensitivity to puromycin as a criterion, evidence was obtained that most of the polyribosomes in hepatoma 7800 were active in vivo. 5. Actinomycin, azaguanine and carbon tetrachloride caused marked conversion of polyribosomes into inactive monomers and dimers in the host liver and moderate conversion in the hepatoma. 6. Significant accumulation of ferritin and shifts in the mean polyribosome size to the lighter species occurred in the host liver of rats bearing large hepatomas.