Between 80 and 90% of the 18-22S Newcastle disease virus intracellular RNA molecules contain poly(A) sequences. Electrophoresis of the 18S RNA in formamide-polyacrylamide gels resolves five species resolved by electrophoresis in aqueous gels. Thus, these five RNA species are probably unique size classes of RNA and not different conformations of the same RNAs. They are of sufficient size to code for the five smaller Newcastle disease virus proteins, and their combined molecular weights represent 60% of the viral genome-a value identical to that obtained by annealing 18-22S RNA with genome RNA. Formamide or heat treatment of the 22S RNA converts most of it into species with migration rates similar to those of the 18S species. Thus, the 22S RNA may not contain unique RNA species.
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