Browsing Pathways

Thyroid hormone synthesis is a process that occurs in the thyroid gland in humans that results in the production of thyroid hormones which regulate many different processes in the body, such as metabolism, temperature regulation and growth/development. Thyroid hormone synthesis begins in the nucleus of a thyroid follicular cell, as thyroglobulin synthesis occurs here and is transported to the endoplasmic reticulum. From there, thyroglobulin transported through endocytosis into the intracellular space, and then transported through exocytosis to the follicle colloid. There, thyroglobulin is joined by iodide that has been transported from the blood, through the thyroid follicular cell and arrived in the the follicle colloid using pendrin, and hydrogen peroxide to be catalyzed by thyroid peroxidase, creating thyroglobulin + iodotyrosine. Then, iodide, hydrogen peroxide and thyroidperoxidase create thyroglobulin + 3,5-diiodo-L-tyrosine. Thyroglobulin+3,5-diiodo-L-tyrosine then joins with hydrogen peroxide and thyroid peroxidase to create thyroglobulin + 2-aminoacrylic acid and thyroglobulin+liothyronine. Thyroglobulin + liothyronine then goes through two processes, the first being its transportation into the cell and undergoing of proteolysis, which is followed by liothyronine being transported into the bloodstream. The second process is thyroglobulin + liothyronine being catalyzed by thyroid peroxidase and resulting in the production of thyroglobulin + thyroxine. Thyroglobulin + thyroxine is then transported back into the cell, undergoes proteolysis, and thyroxine alone is transported back out of the cell and into the bloodstream.