Fig 6.

Schematic representation of a two-step model for Alix function in virus assembly and budding. In the first step, Alix is recruited by Gag to the plasma membrane during assembly through interaction between its V domain and the (L)YPXnL motif in p6 and Alix is thus anchored at the membrane (left). Whether NC binds Bro1 during this step or not is unclear, since it was insufficient to locate Alix to the membrane when the LYPXnL motif was disrupted (18). In the second step, we propose that the NC-Bro1 interaction occurs in the budding neck and is followed (or accompanied) by the recruitment of CHMP4B (right). Basic residues found in both NC and Bro1 proteins mediate binding, and RNA (in red) plays the role of the negatively charged factor that bridges this interaction.