Recognition of a TSHR conformational epitope by MS-1. MS-1 recognized the native conformation of hTSHR antigen on unfixed CHO-hTSHR cells (a), but not on fixed CHO-hTSHR cells (b). In contrast to MS-1, mouse monoclonal TSHR-Ab RSR-1 (29) recognized both the native (c) and fixed (d) conformations of the hTSHR. Thin and thick lines indicate staining on CHO and CHO-hTSHR cells, respectively. Fluorescence intensity was measured in FL-1.