Keywords: Thyroid hormone synthesis-it.svg it Sintesi degli ormoni tiroidei thyroid hormones Reference Chapter 48 SYNTHESIS OF THYROID HORMONES in cite book Walter F PhD Boron Medical Physiology A Cellular And Molecular Approaoch Elsevier/Saunders 2003 1300 1-4160-2328-3 Explanation Thyroglobulin is synthesized in the rough endoplasmic reticulum and follows the secretory pathway to enter the colloid in the lumen of the thyroid follicle by exocytosis Meanwhile a sodium-iodide Na/I symporter pumps iodide I<sup>-</sup> actively into the cell which previously has crossed the endothelium by largely unknown mechanisms This iodide enters the follicular lumen from the cytoplasm by the transporter pendrin in a purportedly passive manner <ref>http //www touchbriefings com/pdf/2782/rousset pdf How Iodide Reaches its Site of Utilisation in the Thyroid Gland “ Involvement of Solute Carrier 26A4 Pendrin and Solute Carrier 5A8 Apical Iodide Transporter - a report by Bernard A Rousset Touch Brieflings 2007</ref> In the colloid iodide I<sup>-</sup> is oxidized to iodine I<sup>0</sup> by an enzyme called thyroid peroxidase Iodine I<sup>0</sup> is very reactive and iodinates the thyroglobulin at tyrosyl residues in its protein chain in total containing approximately 120 tyrosyl residues In conjugation adjacent tyrosyl residues are paired together The entire complex re-enters the follicular cell by endocytosis Proteolysis by various proteases liberates thyroxine and triiodothyronine molecules which enter the blood by largely unknown mechanisms Additional references for details reflist Mainly own Source image for nucleus derivative <gallery> File Plant cell structure svg svg Public Domain license </gallery> Mikael Häggström 2011-06-16 Thyroid hormone synthesis zh-cn svg thumb left png-format Italian translation layers Fulvio314 Thyroid_hormone_synthesis svg Laboratorio grafico Cc-zero Thyroid |