FIG. 2.
Identification of polyprotein ORF1ab precursors and products of MHV A59-infected HeLa-MHVR cells labeled in the absence (−) or presence (+) of protease inhibitor E64d. (A) Infected cells were either untreated or treated with 400 μg of protease inhibitor E64d per ml at 3 hpi for 30 min. Then, proteins were labeled with Trans35S-label in the presence or absence of E64d for 2 h. Total lysates were prepared and subjected to immunoprecipitation with the indicated antisera. Products were analyzed by electrophoresis as in Fig. 1. Lanes 5 and 6 provide a longer exposure of the results depicted in lanes 3 and 4. Sizes are shown on the left in kilodaltons. (B) Schematic diagram depicting the MHV A59 genome and our current understanding of the proteolytic processing cascade of the RNA-dependent RNA polymerase (ORF1ab) polyprotein. The locations of antiserum determinants and riboprobes is indicated above the MHV genome. aa's, amino acids.