<unk>  hormone synthesis, with<unk>  performing the oxidation step seen at center-left in the image. Inorganic iodine enters the body primarily as iodide, I−. After entering the<unk>  follicle (or<unk>  follicular cell) via a Na+/I− symporter (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid via pendrin, after which<unk>  oxidizes iodide to atomic iodine (I) or iodinium (I+). The "organification of iodine," the incorporation of iodine into thyroglobulin for the production of<unk>  hormone, is nonspecific; that is, there is no<unk> -bound intermediate, but iodination occurs via reactive iodine species released from<unk> . The chemical reactions catalyzed by<unk>  occur on the outer apical membrane surface and are mediated by hydrogen peroxide.
Thyroid peroxidase
Alpha-fetoprotein
Parathyroid hormone-related protein
Parathyroid hormone
Thyroglobulin
Mammaglobin
Androgen prohormone
Carcinoembryonic antigen