Figure 4.

1 inhibits the basal activities of constitutively active mutant TSHRs (CAMs). HEK-EM 293 cells transiently expressing wild-type TSHRs and mutant TSHRs S281N, M453T, I568T, or F631T, were incubated without 1 (control activity) or with the noted concentrations of 1 in HBSS with 1 mm IBMX for 60 min. Subsequently, cells were lysed and cAMP levels were measured by ELISA. The control activities of the CAMs were as follows: S281N, 15 ± 3.3-fold; M453T, 27 ± 7.3-fold; I568T, 24 ± 0.71-fold; and F631I, 20 ± 4.5-fold above wild-type TSHR basal activity. The data from two independent experiments with duplicate samples are shown as percentage of control activities.