Table 1. Functional characterisation of cAMP accumulation by the TSHR mutants.

TSHR	Inducible activity a			Relative constitutive activity e
	EC50 b	Emax c	CSE d
WT	0.4 ± 0.2	80 ± 6	39 ± 4	1
L2.58P	-	-	-	1.7 ± 0.3
L2.59P	0.8 ± 0.4	70 ± 4	27 ± 3	0.23 ± 0.05**
I2.60P	0.8 ± 0.2*	84 ± 3	23 ± 2	0.31 ± 0.08*
A5.50P	0.6 ± 0.2	88 ± 6	31 ± 2	0.26 ± 0.03**

^a HEK-293 cells were transiently transfected with variable amounts of the pcDNA3.1 plasmid containing WT or mutated TSHRs, adjusted to yield similar cell surface expression in order to minimize the effect of the receptor concentration on the measured parameters. The WT_max control was obtained by transfecting HEK-293 cells with a 10 fold increase in the amount of pcDNA3.1 plasmid encoding WT TSHR. The data are given as the mean ± SEM of three independent experiments, each carried out in triplicates.

^b EC50 is expressed in mUI/ml. The EC50 for the WT_max control is 0.2 ± 0.1.

^c Emax values are expressed as a percentage of the WT_max control.

^d The cell surface expression (CSE) was quantified by flow cytometry measurements. CSE levels are expressed as a percentage of the WT_max control

^e The relative constitutive activity of the TSHR mutants was estimated from the ratio of the slopes in the linear regression of the basal cAMP level as a function of the cell surface expression for mutated and WT receptors. The constitutive activity of the WT control is set to 1. The data are given as the mean ± SEM of three independent experiments, each carried out in triplicates.