FIG. 3.

Cleavage of the R236L gp41 CT by WT and PIR PR. (A) 293T cells were transfected with WT or the R236L mutant molecular clones encoding WT or PIR PR. Cell and viral lysates were prepared as described previously (28) and subjected to immunoblotting with the 2F5 anti-gp41 monoclonal antibody. To evaluate the size of the truncated gp41 from the R236L Env mutant, gp41 CT truncation mutants CTdel-144 (144) and CTdel-104 (104) (13, 16, 20) were included for comparison. (B) 293T cells were transfected with WT or AME-resistant mutants (P203L, S205L, R236L, PIR/R236L), and viral lysates were subjected to immunoblotting with the Fitzgerald polyclonal anti-gp41 antibody or the anti-gp41 monoclonal antibody NEA-9303 (19) as described previously (28). Positions of gp160, gp41, and the gp41 N-terminal fragment (NTF) and C-terminal fragment (CTF) are shown. On the right side of the Fitzgerald blot is an overexposed lane of the R236L mutant (R236L o.e.) that shows the ≈13-kDa CTF for this mutant. Molecular mass markers are indicated.