FIG. 1.

The E1B-55K and E4orf6 proteins are required for efficient viral late protein synthesis. (A) HeLa cells were mock infected or infected at an MOI of 10 PFU per cell with wild-type dl309, E1B-55K mutant virus dl1520, or the E4orf6 mutant virus dl355*. At the times indicated, cells were pulse-labeled for 1 h with radioactive amino acids. Proteins from 10⁴ cells (per lane) were resolved by SDS-PAGE and visualized by exposure to X-ray film. Labels for hexon (Hx), penton base (Pt), fiber (Fb), and E2A DNA-binding protein (DBP) are shown at the right of the image. The results are representative of at least three experiments. (B) The rate of hexon synthesis is shown as a function of time postinfection. The radioactivity present in the band corresponding to hexon at 120 kDa was quantified from an image obtained by phosphorescence imaging. The background of cellular protein synthesis was subtracted from each lane's hexon measurement. The rate of hexon synthesis measured at 36 h postinfection in cells infected with dl1520 was set to a value of 1.