Thyroidal Iodoproteins in Pendred's Syndrome

Abstract

The distribution of 127I, 125I, or 131I, and protein was studied in thyroid tissue from 3 patients with Pendred's syndrome. In each of these patients a significant amount of trapped iodide was dischargeable after administration of perchlorate. Two specimens (nodular and paranodular tissue) were studied from each patient. Iodinated insoluble protein comprised 6.4–33.1% of the total radioactive iodine in the homogenates. More participate labeled iodine was present in the nodular tissue, per g of tissue, as compared to paranodular tissue. Nearly ⅓–½ of the total 127I was incorporated into the particulate protein. The pattern of protein distribution followed closely that of stable iodine. In the nodular tissue it was found that the insoluble protein had more labeled iodine per μg of 127I than in the soluble fraction. After 3 weeks of a tracer dose the particulate protein had more labeled iodine per g than after 24 hr of labeling. The particulate iodoprotein was solubilized with trypsin and could be separated from normal thyroglobulin by gel nitration. It also behaved differently from thyroglobulin in agar plates when tested again antisera. In both specimens of thyroid tissue (nodular and paranodular) less than 15% of total soluble protein was in the 19S peak; in one specimen of nodular tissue no detectable 19S protein could be found in the supernatant. It is suggested that patients with Pendred's syndrome may have iodide organification and an inherited disorder affecting normal thyroglobulin synthesis.