Figure 7.

Effect of β-truncated constructs on cAMP generation. HEK-293 cells were transiently transfected with HA-TSHR and the respective β-constructs. After 48 h, the total intracellular cAMP generated was measured before and after 1 h of TSH stimulation (100 μU/ml). The basal constitutive cAMP of the WT HA-TSHR cells was 322 ± 43 fmol/well and was expressed as 100%. The β-subunit constitutive cAMP activities were low showing values of only 71–84 fmol/well. This low level likely reflects the degree of transient expression and needs further study by determining their specific constitutive activity (21). Cotransfection of the β-constructs with the full-length receptor compromised TSH responsiveness of the WT receptor as evidenced by the marked decrease in stimulated cAMP generation. The data shown here are an average of three independent experiments. NS, Not significant (P > 0.05).