Solubilization, Purification, and Partial Characterization of Thyrotropin Receptor from Bovine and Human Thyroid Glands*

In an attempt to purify the thyroid receptor for TSH and to study interaction with the thyroid-stimulating antibody (TSAb) of graves' disease, we used both bovine and human thyroid glands. With either tissue, the 10,000 X g pellet of homogenized material was solubilized with 0.5% Triton N-101; excess Triton was removed by Amberlite XAD-2, and purification was effected by TSH affinity chromatography, followed by gel filtration on Sepharose 6B. Greatest purification was achieved with bovine tissue; this receptor preparation was 183-fold concentrated over the starting material, but contained only 6% of the original TSH-binding activity, due in part to spontaneous loss over the 4 days required for processing. On polyacrylamide gel electrophoresis, there were at least three protein bands, one of which was probably a subunit of thyroglobulin. Purified immunoglobulin G with thyroid-stimulating antibody activity inhibited the binding of TSH at all stages of purification of the receptor.