FIG. 3.

Molecular analysis of R-peptide processing in selected Env proteins. HEK-293T cells were cotransfected with pHGIN plasmids encoding the indicated Env variants (see Fig. 1A) and with plasmid pHR-CMVΔ8.2. Two days after transfection, cell culture supernatants were harvested and virus particles were concentrated by ultracentrifugation. Virus particles were separated in sodium dodecyl sulfate-16% polyacrylamide gels, transferred to a nitrocellulose membrane, and stained with anti-MLV TM antibodies. (A) Inhibition of R-peptide processing by saquinavir. Where indicated, transfected cells were cultivated in the presence of saquinavir (Saq.). (B) Western blot analysis of point mutants of clones 2 and 4. Stop codons are indicated by asterisks.