Topic 5 : Biochemical activity of the thyroid and parathyroid hormones

the thyroid gland produces __ and ___

thyroxine and triiodothyronine (T3 and T4)

synthesis of thyroid hormone steps:

1. thyroglobulin is exocytosed 2. Na/K ATPase drived pump concentrates iodide in thyroid cells 3. iodide is transported to the follicle lumen 4. iodide is oxidized to I+ by a thyroperoxidase found only in thyroid tissue 5. the addition of I+ to tyrosine residues of thyroglobulin is catalyzed by the same enzyme, leading to the production of thyroglobulin containing monoiodotryosl (MIT) and diiodotryosyl (DIT) residues

which of the two is more important, T3 or T4?

T3

which of the two is more abundant, T3 or T4?

T4

thyroid hormones are synthesized from tyrosyl residues in ___

throglobulin