Figure 2.

Autoradiogram of gel analysis. In vitro packaging of labeled plus strands showing competition for packaging by RNA that is not packaged. Equal amounts of ³²P-labeled transcripts of plasmids pLM658 and pLM656 were used for segments S and M, respectively. Plasmid pLM1157, which yields a 1.5-kb transcript, was used for segment L because it packages better than normal segment L. The packaging of the three segments is illustrated in lane 1, which shows an autoradiogram of an agarose gel analysis of a packaging mixture that had been treated with RNase I to degrade any unpackaged RNA. The conditions of packaging were as described (12). The effects of competition on packaging are shown in lanes 2 and 3, where a 20-fold excess of competitor RNA is added. In lane 2 the RNA is a normal segment M truncated at the SalI site at 1192. In lane 3 the RNA is derived from plasmid 794 also truncated at 1192. Plasmid pLM794 produces a transcript with a deletion of nucleotides 11–43. In lanes 4 and 5 the packaging of the competitor RNAs are shown in the absence of the normal plus strands.