Fig 1.

HIV-1_AD8 Env regions altered in this study. Schematic representations of the HIV-1_AD8 Env are shown, with gp120 and gp41 subunits designated. The proteolytic cleavage site [(508)REKR(511)] between gp120 and gp41 is colored red. The gp120 variable regions (V1–V5) and conserved regions (C1–C5) are indicated. The following elements are labeled: SP, signal peptide; FP, fusion peptide; HR1 and HR2, heptad repeat regions 1 and 2; MPER, membrane-proximal external region; TM, transmembrane region; CT, cytoplasmic tail. The N-linked glycosylation sites are depicted above the Env diagram. The sequences in V1 and V2 (A) and the Env region surrounding the gp120-gp41 cleavage site (B) are shown. The HIV-1_AD8 Env amino acids are numbered according to standard nomenclature, referring to the prototypic HXB2 sequence (94). In A, the N-linked glycosylation sites in the V1/V2 region, several of which are modified in this study, are colored purple, and are numbered.