Comparison of the Nuclear Ribonucleoproteins Containing the Transcripts of Adenovirus-2 and HeLa Cell DNA

A method was devised allowing the preparation of hnRNA-containing ribonucleproteins (hnRNP) from HeLa cells infected with adenovirus type 2 under conditions where the extraction of viral replication complexes was minimal. Approximately 60% of the RNA from such hnRNP hybridized with adenovirus DNA. The hnRNP from infected cells had the same general characteristics as those from uninfected cells. Their size was heterogeneous (30–260 S) and depended upon that of their RNA. Their CsCl densities were identical (1.39–1.40 g/ml), indicating the same protein: RNA ratio. Their proteins were found in the same molecular weight range, between 25000 and 200000. The major proteins of hnRNP from HeLa cells were present in hnRNP from adenovirus-infected cells. As 60% of the cellular RNA was replaced by adenovirus RNA in hnRNP, this indicated that there was not stringent specificity in the RNA-protein interactions. The relative proportions of the proteins were identical in both cases, suggesting that the hnRNP assembly was independent of nucleotide sequences at least for the major proteins. The hnRNP from infected and uninfected cells differed by the size of their RNA, which was larger after infection, and by the presence of six additional minor polypeptides after infection. However, it cannot be excluded that the presence of these polypeptides in hnRNP resulted from non-specific adsorption.