TPO g TPo g METABOLIC STEP INHIBITOR g HOI a lodide transport CIO, SCN- lumen B lodination PTU MMI EO C Coupling PTU MMI D Colloid resorption Colchicine Li2+,I- Cytochalasin B E Proteolysis 00d F Deiodination of DIT Mit Dinitrotyrosine PTU apical membrane G Deiodination of T4 cel Follicular LE MIT DIT. 5.de- iodinate 4 GT3 Follicular lumen containing Tg ECF A basement membrane - Metabolism of thyroid hormones