Thyroxine synthesis pathway

Thyroxine synthesis is a complex multi-step biochemical pathway that occurs in thyroid follicular cells for the production of thyroid hormones T3 and T4. The process involves five main steps: (1) synthesis of thyroglobulin protein in the endoplasmic reticulum and its secretion into the follicular lumen, (2) active uptake of iodide from blood via the sodium-iodide symporter (NIS) and transport into the colloid via pendrin, (3) oxidation and organification of iodide by thyroid peroxidase (TPO) using hydrogen peroxide, followed by iodination of thyroglobulin tyrosine residues to form monoiodotyrosine (MIT) and diiodotyrosine (DIT), (4) coupling of iodinated tyrosines by TPO to generate T3 and T4 (T4 from two DITs, T3 from MIT and DIT), and (5) endocytosis of iodinated thyroglobulin, lysosomal proteolysis, and release of T3 and T4 into circulation. The entire process is regulated by thyroid-stimulating hormone (TSH) through the hypothalamic-pituitary-thyroid axis. This is a pathway involving multiple protein targets including NIS, pendrin, TPO, DUOX2, and thyroglobulin, rather than a single molecular target.

Other names

Thyroid hormone synthesisT4 synthesisThyroid hormone biosynthesis pathway