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Thyroid hormones act on nearly every cell in the body. They act to increase the basal metabolic rate, affect protein synthesis, help regulate long bone growth (synergy with growth hormone) and neural maturation, and increase the body's sensitivity to catecholamines (such as adrenaline) by permissiveness. [12]
Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment of the thyroid follicles, accounting for approximately half of the protein content of the thyroid gland. [5]
Unlike the Wolff–Chaikoff effect, the Plummer effect does not prevent the thyroid from taking up radioactive iodine, e.g. in the case of nuclear emergencies.Therefore, "plummering" with high-dose iodine is only effective in a short time window after the release of radionuclides. [9]
Thyroid hormone synthesis. [ 2 ] Follicular cells take up iodide and amino acids from the blood circulation on the basolateral side, synthesize thyroglobulin and thyroperoxidase from amino acids and secrete these into the thyroid follicles together with iodide.
Thyroid peroxidase, also called thyroperoxidase (TPO), thyroid specific peroxidase or iodide peroxidase, is an enzyme expressed mainly in the thyroid where it is secreted into colloid. Thyroid peroxidase oxidizes iodide ions to form iodine atoms for addition onto tyrosine residues on thyroglobulin for the production of thyroxine (T 4 ) or ...
Organification is a biochemical process that takes place in the thyroid gland. It is the incorporation of iodine into thyroglobulin for the production of thyroid hormone, a step done after the oxidation of iodide by the enzyme thyroid peroxidase (TPO) [1] Since iodine is an inorganic compound, and is being attached to thyroglobulin, a protein, the process is termed as "organification of iodine".
The final step in thyroxine synthesis involves the free radical mediated coupling of two DIT residues, catalyzed by TPO, to form T 4 while still attached to the Tg backbone. [5] [6] When thyroid hormone is needed, Tg is internalized by thyrocytes, and proteolytic enzymes in lysosomes cleave the T 4 from Tg, allowing for its release into the ...
DIT is a modulator of the enzyme thyroid peroxidase (which is involved in the production of thyroid hormones). [1] Triiodothyronine is formed, when diiodotyrosine is combined with monoiodotyrosine (in the colloid of the thyroid follicle). Two molecules of DIT combine to make the thyroid hormone thyroxine ('T4' and 'T3').