Thyroglobulin

Thyroglobulin is a 660 kDa dimeric glycoprotein produced by thyroid follicular cells and utilized entirely within the thyroid. It serves as a substrate for the synthesis of thyroid hormones, thyroxine (T4) and triiodothyronine (T3), and acts as a storage form for inactive thyroid hormones and iodine in the follicular lumen of thyroid follicles.