FIG. 4.
Effects of ubiquitin mutants on VLP production by a minimal HIV-1 Gag construct carrying the Ebola virus L domain. HeLa cells were cotransfected with Δ-ZWT-Eb, together with an expression vector for WT or mutant ubiquitin, as indicated. To compare VLP production, the cells were labeled with [35S]methionine, and particulate material released into the culture medium was pelleted through sucrose and analyzed by SDS-PAGE. Cell-associated Gag protein was detected by immunoprecipitation with anti-CA antiserum.