FIG. 9.

Denaturation of the gp120-sCD4 complex. In 25 μl of binding buffer containing 5% BSA, JRFL gp120 with or without sCD4 was incubated at the indicated temperature for 15 min. The protein was then cooled at room temperature (or on ice, with similar results) and added to cells expressing CD4, CCR5, or pcDNA3. Binding was conducted for 1 h at RT. Binding to CD4 on the surface of cells was conducted in the absence of sCD4. Denaturation temperatures above 65°C resulted in protein aggregation that caused high nonspecific binding. Results shown are from a representative experiment repeated twice.