New HIV particles are assembled at the plasma membrane of infected cells. Gag proteins (shown in shades of orange in the animation) associate with one another on the membrane to form hexameric lattices that cause the membrane to start to bend.
Additional proteins are recruited that are needed at different points in the budding process. AMOT (shown in orange and purple) is recruited at an early stage, and plays a role in tagging gag proteins with a chain of ubiquitin proteins (shown in red). Later, ESCRT-I (faded purple) and ALIX (blue/purple) are recruited to the budding particle. These proteins are involved in recruiting ESCRT-III proteins (light blue) which polymerize at the bud neck and are responsible for membrane fission.