Figure 2.

Kinetics of association and dissociation of ¹²⁵I-hCG to and from cells expressing the myc-hLHR-wt or myc-hLHR-L457R. 293T cells were transiently co-transfected with Dynamin-K44A (to prevent internalization) and either the myc-hLHR-wt (□) or myc-hLHR L457R (▲) as previously described (24). In the top panel the cells were incubated with ¹²⁵I-hCG (2.5 nM, Kd = 1-3 nM) at 37°C and the amount of hormone bound was determined at the times indicated. In the bottom panel the cells were preincubated with ¹²⁵I-hCG (2.5 nM, Kd = 1-3 nM) for 1h at 37°C and then washed to remove the free hormone. The cells were placed back in medium without hormone (t = 0) and incubated at 37°C. The amount of hormone that remained bound to the cells was determined at the times indicated and expressed as % of the amount of hormone bound at t = 0. Each point is the mean ± SEM of 3 independent experiments.