Characterization of the 5'-terminal cap structures of early simian virus 40 mRNA.

Early simian virus 40-specific mRNA was isolated from lytically infected and stably transformed cells and analyzed with respect to the 5'-terminal cap content. An analogous diversity of capped structures was found in both RNA preparations, indicating that 5'-terminal heterogeneity is not limited to late simian virus 40 RNA transcription but concerns a more general feature. Correlation of our data with previously published results of characterization of early mRNA's by reverse transcription allowed a tentative localization of the major 5' termini on the viral genome.