Inhibition of avian myeloblastosis virus reverse transcriptase by an RNA-binding protein from plasma membranes of normal and tumor cells.

Purified plasma membranes from normal rat liver, a rat hepatoma and a rat hepatic fibrosarcoma have been shown to contain a protein which drastically inhibits avian myeloblastosis virus reverse transcriptase activity. The inhibition is caused by the binding of the protein to the template. The binding and the consequent inhibition of enzyme activity are template-specific; copying of RNA templates is inhibited whilst that of DNA templates remains unaffected. Investigations using different templates suggest that the inhibitory protein has a stronger binding affinity for G, C-rich templates. The inhibitor appears to have a wide distribution in plasma membranes from diverse sources.