FIG. 4.

The length rather than a specific sequence of the cytoplasmic domain results in increased 17b binding. We engineered two Env proteins with a stop codon at position 733 for HXB (HXB-stop) or 89.6 (89.6-stop). A 17b binding assay was performed to compare the parental clones (wild type [wt]) with the stop constructs as described in the legend to Fig. 2. The results were normalized to the amount of binding obtained with 8x Env set to 100%. The data are compiled from three experiments each done in triplicate; standard errors of the mean are shown. Asterisks indicate statistical significance (t test; two-tailed, assuming unequal variances; P < 0.05).