FIG. 1.

Immature HIV-1 and subviral HIV-1 Gag particles incorporate actin molecules. (A) Immature HIV-1 particles were harvested after treatment of infected T cells with protease inhibitor and then incubated with 0.5% Triton X-100 prior to centrifugation on a 30 to 60% (wt/wt) sucrose gradient for 30 min. The lower panel shows a Western blot probed with rabbit antiactin, and the upper (larger) panel shows the same blot subsequently probed with mouse anti-CA. 1 and 13 indicate the top and bottom fractions, respectively. The peak fraction containing p55 and actin corresponded to 42.5% sucrose on this rate zonal gradient. (B) HIV-1 Gag particles were harvested after expression of the Gag open reading frame in insect cells and separated on a 30 to 60% (wt/wt) sucrose gradient for 30 min. The lower panel shows a Western blot probed with rabbit antiactin, and the upper (larger) panel shows a parallel blot probed with mouse anti-CA. 1 and 16 indicate the top and bottom fractions, respectively. The peak fraction containing p55 and actin corresponded to 37.5% sucrose on this rate zonal gradient. (C) Gradient-purified Gag particles from an experiment similar to that shown in panel B using the wild type (lane 1), ΔMA (lane 2), and Δp6 (lane 3). The lower panel shows a Western blot probed with rabbit antiactin, and the upper (larger) panel shows a parallel blot probed with mouse anti-CA.