FIG. 2.
BAF is present in HIV-1 virions at low levels. (A) HIV-1 virions produced from HIVMN-infected H9 cell lines were either mock treated (−) or digested with the nonspecific protease subtilisin (+). In parallel, microvesicles were prepared from uninfected H9 cells and either mock treated (−) or treated with subtilisin (+). Protein extracts from all samples were then analyzed by immunoblotting using antibodies to human BAF, CD45 (microvesicle marker), and p24 (HIV-1 capsid protein) (α-BAF, α-p24, and α-CD45, respectively). (B) Stoichiometry of BAF in the virion. Protein extracts from subtilisin-digested HIV-1 virions and known amounts of recombinant IN, MA, and BAF proteins were immunoblotted using antibodies specific for each protein. The number of molecules per unit volume of purified virions was calculated and expressed as a ratio relative to BAF.