In vitro synthesis of adenovirus type 5 T antigens. I. Translation of early region 1-specific rna from lytically infected cells.

Translation of early RNA specific for the leftmost early region 1 of adenovirus type 5 DNA in a rabbit reticulocyte cell-free system resulted in the synthesis of proteins with the following molecular weights: 65,000 (65K), 54K, 42 to 34K, 29K, 25K, 19K, and 18K. All of these proteins could be immunoprecipitated with hamster antitumor serum. The 42 to 34K proteins mapped in early region 1a, and those with molecular weights of 65K, 19K, and 18K mapped in early region 1b. The gene coding for the 54K protein may be localized outside of early region 1. We could not map unambiguously the 29K and 25K proteins. The identification of a 65K protein among products synthesized in vitro suggests that this protein may be identical to the 65K major T antigen present in adenovirus type 5-infected and -transformed cells, and this indicates that it is indeed encoded by the viral genome. This protein is encoded by a 23S mRNA. The other early region 1-specific proteins appear to be encoded by mRNA of approximately 13S, except for the 19K protein, which is synthesized with RNA sedimenting at both 13S and 23S.