SOME DISTURBANCES RELATED TO IODINATION AND UTILIZATION OF THYROGLOBULIN AND 27-S IODOPROTEIN IN NON-TOXIC MULTINODULAR GOITER

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  • 1 January 1978
    • journal article
    • research article
    • Vol. 72  (2) , 155-165
Abstract
The relationships among the thyroid iodoproteins, their biosynthesis in vitro in thyroid slices and the histological structure of a multinodular, sporadic goiter was examined after strumectomy from a euthyroid 51 yr old woman. Using sedimentation methods 27S, thyroglobulin (TG), 12S and 3-8S proteins were found. Besides these, 4 or 5 other proteins with MW from 165,000-36,000 daltons were detected by polyacrylamide gel electrophoresis. The concentration of soluble proteins was very low (3 mg/100 mg wet tissue), particularly TG (0.69 mg/100 mg). The sedimentation constant (18.3S) of goitrous TG was lower than mature 19S-TG and it was poorly iodinated. 27S Iodoprotein was present in the goiter extract. Thyroid slices of goiter tissue incorporated 14C-Leu into proteins and synthesized TG and its subunits. Newly synthesized proteins were rapidly released from the microsomes. Pathohistologically, thyroid colloido-microfolliculare with dystrophic-proliferative changes was noted. In the large follicles filled with colloid, dystrophic alterations in thyrocytes and desquamation of the follicular epithelium were observed. The presence of poorly iodinated, immature TG in nontoxic multinodular, sporadic goiter in the absence of I deficiency, probably results in disturbances in the utilization of TG from the follicular lumen. In the follicular lumen under these conditions it is possible that 27S protein is formed from pre-existing poorly iodinated TG. The inability to resorb colloid may be a cause of nodule formation.

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