FIG. 1.

(A) Schematic representation of gp41. The rectangles marked FP, NHR, CHR, and TM indicate the locations of the fusion peptide, N-terminal HR sequence, C-terminal HR sequence, and TM domain, respectively. Residues 663 to 683 of the extracellular domain, which constitute the Trp-rich region, and the TM domain are shown in the single-amino-acid code. The immediate membrane-proximal LWYIK motif, located at residues 679 to 683, is boxed. The epitopes for the 2F5 and 4E10 MAbs and the locations of the inhibitor peptides are underlined with dark lines. (B) Construction of the LWYIK motif mutant proviruses. Site-specific, oligonucleotide-directed mutagenesis was performed based on the infectious pHXB2RU3 provirus to generate proviral variants with mutations in the LWYIK motif as indicated. Dashes and dots indicate that the residue in that position of the mutant proviruses is identical to or absent from that of the WT provirus, respectively.