Iodide transporter

Certain inorganic monovalent anions, similar in size to I, are also taken up by the thyroid gland and competitively inhibit active iodide transport with the following decreasing potencies ... 

Dal G, Carrasco L, Carrasco N Cloning and characterization of the thyroid iodide transporter. Nature 1996 379 458. 

Kopp P, Pesce L, Sohs-S JC (2008) Pendred syndrome and iodide transport in the thyroid. Trends Endocrinol Metab 19 260-268... 

Fig. 5. Scanning electron micrograph of single crystals of Pa metal grown by iodide transport (Sections II,D and III,C) magnification = 100 x (107).

Protactinium metal was first prepared in 1934 by thermal decomposition of a pentahalide on a hot filament 50). It has since been prepared from PaF4 by metallothermic reduction (Section II,A) with barium 26, 27, 34,102), lithium 40), and calcium 73, 74). However, the highest purity metal is achieved using the iodide transport (van Arkel-De Boer) process (Section II,D). 

The method of choice for the preparation of Pa metal is a somewhat modified van Arkel-De Boer process, which uses protactinium carbide (Section II,C) as the starting material. The carbide and iodine are heated to form protactinium iodide, which is thermally dissociated on a hot filament 12-15). An elegant variation is to replace the filament with an inductively heated W or Pa sphere 109). A photograph of a 1.4-g sample of Pa metal deposited on a radiofrequency-heated W sphere is shown in Fig. 6. From the analytical data presented in Table V, the impurities present before and after application of this modified iodide transport process (Sections II,D and III,C) can be compared. 

III.b.1.1. Anion inhibitors. Perchlorate, periodate, pertechnetate and thiocyanate (a naturally occurring goitrogen) are classified as iodide pump inhibitors, antagonizing iodide transport through competitive inhibition. This effect can be overcome by large dose of iodides. Perchlorate is used to block reuptake of iodide in cases of amiodarone induced hyperthyroidism and for the perchlorate discharge test . 

Monovalent anions such as perchlorate (CI04 ), pertechnetate (Tc04 ), and thiocyanate (SCN ) can block uptake of iodide by the gland through competitive inhibition of the iodide transport mechanism. Since these effects can be overcome by large doses of iodides, their effectiveness is somewhat unpredictable. 

Van Sande J, Deneubourg F, Beauwens R, Braekman JC, Daloze D, Dumont JE (1990) Inhibition of Iodide Transport in Thyroid Cells by Dysidenin, a Marine Toxin, and Some of Its Analogs. Mol Pharmacol 37 583... 

Paire, A., Bernier-Valentin, F., Selmi-Ruby, S., and Rousset, D. (1W7). Characterization of the rat thyroid iodide transporter using anti-peptide antibodies. /. Biol. Chem. 172, 18245-18249. 

The biosynthesis of thyroid hormones involves the trapping of circulating iodide (iodide transport) by the thyroid gland, the incorporation of iodine into tyrosine, and the coupling of iodinated tyrosyl residues to form the thyronines (T4 and... 

Bastomsky, C.H. Thyroid iodide transport, Handbook of Physiology, Vol. Ill, edited by R.O. Greep and E.B. Astwood, Washington, DC, American Physiological Society, 1974, Section 7. 

Welch MJ, Adatepe M, Potchen EJ (1969) An analysis of technetium ( " TcOlJ) kinetics the effect of perchlorate and iodide pretreatment. Int J Appl Radiat Isot 20 437-445 Wolff J, Maurey JR (1962) Thyroid iodide transport. III. Comparison of iodide with anions of periodic group VIIA. Biochim Biophys Acta 57 422-426... 

Iodide transport from the blood into the thyroid acinar cell is accomplished through an energy-requiring, iodide-trapping mechanism that is poorly defined but may involve the Na, K -ATPase coupled to a cotransporter for Na and iodide in the plasma membrane of the acinar cell. 

The rate of iodide transport is influenced by the absolute concentration of iodide within the thyroid cell. An internal autoregulatory mechanism decreases transport of iodide into the cell when the intracellular iodide concentration exceeds a certain threshold and increases transport when intracellular iodide falls below this threshold level. 

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