Iodination and coupling of the hormonogenic tyrosines in thyroglobulin to yield the thyroid hormones T(3) and T(4). 2 H(+) + H2O2 + 2 iodide = diiodine + 2 H2O [thyroglobulin]-L-tyrosine + H(+) + H2O2 + iodide = [thyroglobulin]-3-iodo-L-tyrosine + 2 H2O [thyroglobulin]-3-iodo-L-tyrosine + H(+) + H2O2 + iodide = [thyroglobulin]-3,5-diiodo-L-tyrosine + 2 H2O 2 [thyroglobulin]-3,5-diiodo-L-tyrosine + H2O2 = [thyroglobulin]-dehydroalanine + [thyroglobulin]-L-thyroxine + 2 H2O [thyroglobulin]-3,5-diiodo-L-tyrosine + [thyroglobulin]-3-iodo-L-tyrosine + H2O2 = [thyroglobulin]-3,3',5-triiodo-L-thyronine + [thyroglobulin]-dehydroalanine + 2 H2O Binds 1 Ca(2+) ion per heterodimer. Binds 1 heme b (iron(II)-protoporphyrin IX) group covalently per heterodimer. Hormone biosynthesis; thyroid hormone biosynthesis. Interacts with DUOX1, DUOX2 and CYBA. Heme is covalently bound through a H(2)O(2)-dependent autocatalytic process. Heme insertion is important for the delivery of protein at the cell surface (By similarity). Cleaved in its N-terminal part. N-glycosylated; contains mannose and N-acetylglucosamine. Belongs to the peroxidase family. XPO subfamily.