Fig. 2.

Schematic of HIV-1 Gag indicating major functional motifs. The myristic acid and highly basic region of MA mediate membrane interactions of Gag. Residues in MA that have been shown to affect Env incorporation are indicated with dashed vertical lines. CA is divided into N-terminal and C-terminal domains, NTD and CTD, respectively. The NTD promotes pentamer formation, while the CTD, which also contains the MHR, is required for CA dimerization and multimerization. NC contributes to Gag assembly by binding nucleic acid, typically the viral genome, via its zinc finger motifs, leading to long-range Gag multimerization. p6 contains the late domains PTAP and YPXL, which bind TSG101 and ALIX, respectively, thereby recruiting the ESCRT machinery to facilitate virus budding from the cell membrane. MA, red; CA, blue; NC, green; p6, orange. Spacer peptides SP1 and SP2 are indicated, as is the approximate length of the Gag precursor (500 amino acids)