Fig. 5

Prominent mutations in gp120 and gp41 observed in PIE12-trimer resistant viruses. The primary structure of the Env precursor, gp160, is depicted, with HXB2 (UniProtKB P04578) numbering. The gp41 N- and C-peptide regions are numbered according to [45]. gp160 is processed into two non-covalently associated subunits, the surface gp120 (orange) and the membrane-spanning gp41 (blue). gp120 comprises five constant domains (C1–C5) and five variable domains (V1-V5). gp41 contains a fusion peptide (FP), an N-peptide region that forms the N-trimer coiled coil (N), a C-peptide region (C) that together with the N-trimer forms a 6-helix bundle in the post-fusion state, a membrane-proximal external region (MPER), a transmembrane domain (TM), and a cytoplasmic tail (CT). The primary resistance mutations (Q577R/N/K) are represented in red, and candidate resistance and fitness compensation mutations are shown in black. Mutations denoted by * are within the Rev Response Element (RRE)