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. 2008 May 2;4(5):e1000057. doi: 10.1371/journal.ppat.1000057

Figure 3. Role of the proteasome ubiquitylation system in regulation of SIV infectivity by Vpx.

Figure 3

(A) Identification of ubiquitylated residues in Vpx. Wild type and lysine mutant Vpx proteins (HA tag) were expressed in 293T cells expressing Histidine-tagged ubiquitin. (B) Susceptibility of primary macrophages to infection by SIVΔvpx packaging either wild type Vpx or lysine substitution mutants of Vpx. Vpx proteins were packaged after co-transfection of SIVΔvpx proviral DNA with plasmids expressing wild or lysine mutant Vpx proteins or GFP as a control. Virus infection was gauged from quantitation of late viral cDNAs and 2-LTR cDNAs 48 h post infection (error bars are s.d. of 3 replicate measures of a single DNA sample). (C) Packaging of wild type and non-ubiquitylated Vpx proteins in virus particles (upper panel). The presence of Vpx in gradient purified virions was determined by Western blotting with an HA antibody (lower panel).