The two central protein-binding domains of 90K are required and sufficient for the anti-HIV-1 activity of 90K. (A) Schematic of 90K protein organization and of 90K-myc variants. (B) 293T cells were transfected with the indicated constructs, and expression was verified by Western Blotting using an anti-myc tag antibody. (C) 293T cells were cotransfected with pBR.HIV-1 NL4.3-IRES GFP and the indicated constructs. Two days post transfection, supernatants were analyzed for particle infectivity, defined as infectivity per ng p24. (D) Sucrose cushion-purified virions of three experiments were analyzed by immunoblotting. Shown is the relative gp120 incorporation, as measured by Infrared imaging-based quantification of the amount of gp120 per p24. The signal intensity in absence of 90K expression was set to 100%. (E) Cell lysates were analyzed by immunoblotting. Shown is the percentage of processed gp120, as measured by Infrared imaging-based quantification of the amount of gp120 per (gp120 + gp160). The bar diagrams show the arithmetic means ± S.E.M. of six independent experiments. **: p < 0.02 (Student’s T-Test).