Figure 4.

Identification of important residues in the CS-17 epitope. The six nonhomologous residues in the human TSHR (depicted in Fig. 3B) were mutated to those of the porcine TSHR, individually and in different permutations. CS-17 binding to these mutants, stably expressed in HEK293 cells, was examined by flow cytometry using, as a benchmark, mAb 4C1 with a downstream epitope. For brevity, the mutant TSHR are identified by the positions of the mutated amino acid residues. Normal mouse IgG (Con IgG) was included as a negative control. The vertical dashed lines are drawn through the apex of the 4C1 signal to enhance visually the difference with the CS-17 signal, as shown by the horizontal arrows. These data are representative of three experiments.