Figure 4.

A physiological interaction site for the ubiquitin ligase Nedd4 can act as an L domain. HeLa cells were transfected with proviral constructs expressing the L domain-dependent minimal Gag molecule Δ-Z_WT (lane 1), or variants of Δ-Z_WT that contain at the C terminus either RSV p2b^gag (lane 2) or the sequence TAPPPAYATLG from the α subunit of the human ENaC (lane 3). To compare the levels of VLP formation, particulate material released into the medium during metabolic labeling with [³⁵S]methionine was pelleted through sucrose and analyzed directly by SDS/PAGE. In lane 1, the faint band just below the position of the 14 kDa molecular mass marker corresponds to the parental Δ-Z_WT molecule. The arrows indicate the positions of Gag-ubiquitin conjugates.