What is the Origin of Thyroglobulin?

The name is derived from the Greek "thyreos" (shield, referring to the thyroid gland) and "globulin" (a globular protein). Its identity as the essential precursor and storage medium for thyroid hormones was established through early biochemical studies of the thyroid gland's unique ability to concentrate iodine. The term is foundational to understanding the entire process of thyroid hormone biosynthesis.

What is the Mechanism of Thyroglobulin?

The mechanism involves the protein being synthesized and exocytosed into the colloid. There, the enzyme thyroid peroxidase catalyzes the iodination of its tyrosine residues and the subsequent coupling of these iodotyrosines to form the active T4 and T3 hormones, which remain covalently linked to the Tg molecule. Upon stimulation by TSH, the follicular cells reabsorb the iodinated Tg, proteolyze it, and release the active thyroid hormones into the circulation.

Thyroglobulin

Meaning

Thyroglobulin (Tg) is a large, dimeric glycoprotein synthesized exclusively by the thyroid follicular cells and secreted into the follicular lumen, where it functions as the central scaffold for the synthesis and storage of thyroid hormones. It contains the numerous tyrosine residues that are sequentially iodinated to form T4 (thyroxine) and T3 (triiodothyronine). The concentration of Thyroglobulin in the blood is a clinically important biomarker for monitoring differentiated thyroid cancer recurrence.