Figure 3.

Desorption of prebound ¹²⁵I-hFSH by hCG addition is observed in cells cotransfected with hLHR and hFSHR but not in cells transfected separately and then cocultured. HEK293 cells were transiently transfected with cDNAs encoding hLHR and hFSHR at submaximal levels (A) or cells were transfected with the same concentrations of hLHR only or hFSHR only and then cocultured together (B). On the day of the experiment, cells were incubated with a saturating concentration of ¹²⁵I-hFSH (200 ng/mL final concentration). After washing to remove unbound ¹²⁵I-hFSH, cells were incubated for the indicated times at room temperature with buffer only (open squares, dashed lines) or with hCG (500 ng/mL final concentration) (filled triangles, solid lines). At the end of the incubation period, the amount of acid-precipitable ¹²⁵I-hFSH released into the medium was determined. Data shown are the mean ± SEM of triplicate determinations from one experiment representative of 2 independent experiments.