Human Physiology Notes P4

Thyroperoxidase attaches iodine to tyrosil residues. When TSH stimulates the thyrocite it also triggers an endocytoic catcher of material that brings it into the cell that fuses with a lysosome carrying various enzymes that cleave and fold thyroglobin so as to bring the tyrosil residues together. Thyroid hormone is a diphenyl ether with four iodines and iodines are negatively charged atoms. The outer ring is away from the amino side and the inner ring is closer. When these are unattached, T4 is converted to T3. Clinically, if you have thyroid disease, T4 and T3 are not the only things the doctors look at. They also look at reverse T3 which is produced by this unattachment.