thyroglobulin

biochemistry

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July 14, 2026

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Thyroglobulin is an iodine-containing protein found in the thyroid gland. It serves as the precursor for the thyroid hormones thyroxine (T4) and triiodothyronine (T3). The synthesis of these hormones involves adding iodine to tyrosine components within the thyroglobulin molecule.12

Thyroglobulin is stored in the thyroid gland's follicles, forming the thyroid colloid, which acts as a reserve for thyroid hormones. The pituitary gland produces thyrotropin (thyroid-stimulating hormone, TSH), which stimulates the thyroid gland to break down thyroglobulin and release T4 and T3 into the bloodstream. This process is crucial for regulating metabolism and is influenced by a negative feedback mechanism involving circulating thyroid hormone levels.234

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hormone
Biosynthesis
…component of a glycoprotein called thyroglobulin. Thyroglobulin is stored within the gland in follicles as the main component of a substance called the thyroid colloid. This arrangement, which provides a reserve of thyroid hormones, perhaps reflects the frequent scarcity of environmental iodine, particularly on land and in fresh water. Iodine…
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…component of a glycoprotein called thyroglobulin. Thyroglobulin is stored within the gland in follicles as the main component of a substance called the thyroid colloid. This arrangement, which provides a reserve of thyroid hormones, perhaps reflects the frequent scarcity of environmental iodine, particularly on land and in fresh water. Iodine…
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thyroid gland
Anatomy of the thyroid gland
…colloid that contains the prohormone thyroglobulin. The follicular cells contain the enzymes needed to synthesize thyroglobulin, as well as the enzymes needed to release thyroid hormone from thyroglobulin. When thyroid hormones are needed, thyroglobulin is reabsorbed from the colloid in the follicular lumen into the cells, where it is split…
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…colloid that contains the prohormone thyroglobulin. The follicular cells contain the enzymes needed to synthesize thyroglobulin, as well as the enzymes needed to release thyroid hormone from thyroglobulin. When thyroid hormones are needed, thyroglobulin is reabsorbed from the colloid in the follicular lumen into the cells, where it is split…
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