Figure 1.

Overview of the assembly pathway of human immunodeficiency virus type 1 (HIV-1). The viral protein Rev facilitates efficient export of unspliced genomic RNA (gRNA) from the nucleus. Upon entering the cytoplasm, the gRNA can adopt two conformations, which permit either translation or dimerization to form a structure which is selectively packaged by group-specific antigen (Gag). Gag trafficking to the plasma membrane is linked to the mechanism of nuclear export of gRNA, and requires RNA binding to the matrix domain to inhibit binding to intracellular membranes. Multimerized Gag recruits the host endosomal sorting complexes required for transport (ESCRT) machinery for budding, including ALIX, which binds both the p6 and nucleocapsid (NC) domains. Following release immature virions undergo proteolytic maturation (cleavage sites in Gag indicated by arrows) leading to production of infectious virus particles.