Thyroid proteins and hormone synthesis in various benign thyroid diseases: in vivo and organ culture studies.

Abstract

ABSTRACT The iodoproteins were extracted from 61 thyroid glands with signs of various benign diseases. In 59, the solubility properties and ultracentrifugation behaviour of the iodoproteins were normal, although the hormone synthesis was deficient. The incorporation of radioiodine into the hormones (T4* and T3) was smallest when the iodination of thyroglobulin (Tg) was lowest. In these cases the concentration of Tg was less than normal, but is seemed that the disorders of hormone synthesis were correlated with a deficiency in the iodination of Tg. Two goitres were clearly different from the other cases studied; thus anomalies of the iodoproteins are rare. In these two goitres, Tg was virtually absent, although thyroid hormones were synthesized. Electrophoresis on acrylamide gel in one of these goitres showed 3 protein bands corresponding to the light fractions in extracts of normal thyroid tissue. Albumin (F1) was the only iodinated protein of this goitre and seemed to support hormone synthesis. Albumin did not appear to be synthesized by the thyroid tissue since 14C-amino acids were not incorporated into this fraction in organ culture. The other fractions (F2 and F3) did not incorporate radioiodine but appeared to incorporate 14C-amino acids to a slight extent. It is possible that this goitre is able to synthesize the precursors of Tg but not Tg itself.