Identification and mapping of the early gene products of adenovirus type 12

Cytoplasmic RNA was prepared from KB cells early after lytic infection with adenovirus type 12 and virus-specific RNAs were selected by hybridization to endo R·HindIII fragments of Ad12 DNA. The selected RNAs were translated in cell-free systems derived from wheat germ or rabbit reticulocytes and the protein products were analyzed by gel electrophoresis. It was found that the leftmost early region (region EI) of the genome (0–11%) coded for polypeptides with apparent molecular weights (kilodaltons) of 60, 41, a series of proteins between 39 and 23, 19, 17, 16, and 15 kD. The 41-kD protein maps on the left side of region EI, and the 19- and 60-kD proteins probably on the right side of EI. Early region II (62–68%) coded for polypeptides of 60, 52, and 46 kD which probably represent the single-stranded DNA-binding protein and two proteolytic breakdown products. We could not map unambiguously a protein in early region III, but we suspect that a 23-kD protein (and possibly a 16-kD protein) are encoded by this region. Early region IV (91–100%) coded for polypeptides of 14.5 and 13.5 kD. The virus-specific RNA from an Adl2-transformed hamster cell line directed the synthesis of 60-, 41-, 19-, 16-, 15-, 14.5-, and 13.5-kD polypeptides, suggesting that, in addition to early region 1, early region IV is also expressed. A remarkable similarity was observed between proteins synthesized in vitro by Adl2- and Ad5-specific RNA.