Thyroglobulin (Tg) provides the matrix for thyroid hormone biosynthesis. It is a dimeric glycoprotein with a molecular weight of 660,000. Most of the thyroglobulin is present in the thyroid follicular lumen. Thyroglobulin contains 0.1–2.0% iodine and, as a glycoprotein, it contains 8–10% total carbohydrate, with galactose, mannose, fucose, N‐acetyl glucosamine and sialic acid residues. The carbohydrate in the protein is distributed as three distinct units, A, B and C. Tg is synthesized on polysomes on the endoplasmic reticulum near the basal portion of the cell. After phosphorylation and gylcosylation it is vectorially transported to the apical membrane of the cell and deposited into the follicular lumen.

 Antithyroid Drugs