FIG. 6.

Processing of Gag precursor protein Pr55^Gag in wild-type BH10 and mutated viruses containing substitutions of the T12 amino acid in p2. Mutations are represented by single-letter abbreviations of substituted amino acids. (A) Transfected COS-7 cells were labeled with l-[³⁵S]Met and l-[³⁵S]Cys for 30 min and cultured for 1 h. Cells were then lysed, and the lysates were subjected to immunoprecipitation through the use of MAb against CA (p24) Ag. The observed viral proteins, including Pr55^Gag, p41, p39, p25, and p24, are labeled on the right of the gels. To clearly visualize the p25 and p24 proteins in certain mutants, enlarged portions of the gels are shown. Mock-transfected COS-7 cells were also labeled with l-[³⁵S]Met and l-[³⁵S]Cys and serve as a negative control. (B) The intensities of the viral protein bands were quantified through the use of the NIH Image Program, and the percentages of each viral protein in mutant or wild-type virus were plotted. (C) After 1 h in culture, labeled virus particles were pelleted from the supernatants and analyzed on SDS–12% polyacrylamide gels. A portion of the gel was enlarged to clearly show accumulation of p25 protein in the W mutant.