FIG. 3.

Release of core proteins into the soluble fraction after treatment of wild-type and vif mutant virions with NaCl, different pH conditions, or S100 cytosol. Wild-type and vif mutant virions produced in HUT78 cells were permeabilized with melittin (10 μg/ml) prior to addition of reaction buffer containing 50 mM Tris-HCl (pH 7.4) with 0, 50, 150, or 500 mM NaCl, 50 mM Tris-HCl buffered to 7.4 (control pH), 5, 7, or 9, or 0, 1, 5, or 10 μg of S100 cytosol proteins resuspended in 50 mM Tris-HCl (pH 7.4). (A) Endogenous RT activity of wild-type (closed circles) and vif mutant (open circles) (500,000 cpm of exogenous RT units per sample) was measured as described in the legend to Fig. 1. (B) The supernatant and pellet fractions of treated wild-type and vif mutant virions (200,000 cpm of exogenous RT units per sample) were analyzed by Western blotting as described in the legend to Fig. 2. Results are representative of two or three independent experiments using different preparations of virions.