Legend to figure 2: Left. Schematic representation of the equilibria between inactive (R) and active (R*) conformations of TSHR. The triangles indicate the equilibrium point of the wild type receptor (pink) and hypothetical mutants with increasing constitutive activity (brown, red). The situation of a receptor which would be devoid of basal activity is also indicated (blue triangle). Note that the wild type receptor (pink) has basal activity. Right. The concentration action curves corresponding to the hypothetical mutants and wild type receptors are indicated with the same color code.