Figure 1.

Schematic representation of the HIV-1 gp41 domains. Gp41 comprises cytoplasmic, transmembrane (TM) and extracellular domain. Important functional extracellular-domains of gp41 include the fusion peptide (FP), N-terminal and C-terminal heptad repeats (NHR or HR1 and CHR or HR2, respectively). Peptides used in the present study are as follows: P5 (a.a.628–683), Δ Ca2+ bs-P5 (a.a. 628–683) corresponding P5 mutated (bold characters) in the calcium-binding site, P1 (a.a. 648–683), P5L (a.a. 613–683), P7 (a.a.613–746), N36 (a.a. 546–581) LZ (a.a. 560–594). T-20 (a.a. 638–673) is a well-described HIV-1 fusion inhibitor (Enfurvirtide). The residues are numbered according to their position in gp160 of HIV-1_HXB2. The N-ter of T20 (aa 638) located within the calcium-binding site and that of P1 (a.a. 649) are indicated (grey arrow head). The calcium-binding site in P5 and P5 (L) are underlined.