FIG. 1.

(A) Schematic view of HIV_HXB2 gp41 ectodomain showing the structural and functional regions as well as their relative lengths. The fusion peptide (FP), the loop, the N- and C-terminal heptad repeats (NHR and CHR), the pretransmembrane stretch (PTM), and the transmembrane (TM) domain were drawn approximately to scale. The residue numbers correspond to their positions in gp160 of the HXB2 HIV strain. The amino acid composition of the gp41 fragment studied in this work is also indicated. (B) gp41 hairpin conformation scheme showing the membranotropic regions of gp41 (see reference 17).