Evidence that the porcine thyrotropin (TSH) receptor contains an essential disulphide bridge.

The effects of reducing agents on membrane bound and detergent solubilised porcine TSH receptors have been investigated. Both 2-mercaptoethanol and dithiothreitol appeared to inhibit the TSH-binding activity by a direct effect on the TSH receptor itself and Scatchard analysis suggested that this was primarily due to an alteration in TSH-binding capacity. In addition, some binding activity could be recovered by reoxidation of reduced receptor preparations. These results suggest therefore that the porcine TSH receptor contains an essential disulphide bridge.