Size of murine RNA tumor virus-specific nuclear RNA molecules.

About 1% of the total RNA of cell lines producing murine leukemia virus is virus-specific RNA. About one-third of the virus-specific RNA is located within the nucleus. The size distribution of virus-specific RNA was determined before and after denaturation. Before denaturation, virus-specific RNA sequences sedimented as a heterogeneous population of RNA molecules, some of which sedimented very rapidly. After denaturation, most of the virus-specific RNA had a sedimentation coefficient of 35S or lower, but a small fraction of the nuclear virus-specific RNA sedimented more rapidly than 35S RNA even after denaturation.