Sodium Iodide Symporter (NIS)

The sodium-iodide symporter (NIS) is an ion pump that actively transports iodide (I^-) across the basolateral membrane into thyroid epithelial cells. The NIS a member of the sodium/solute symporter family.Active transport of iodine into the thyroid gland is an important step in the process of iodide organification and the formation of triiodothyronine (T₃) and thyroxine (T₄). The symporter is stimulated by TSH, thereby increasing iodine uptake and iodination of tyrosine.The pump symports two sodium ions for every iodide ion. This symporter is driven by low internal sodium concentration in the thyroid epithelial cells, via facilitated diffusion, caused by the sodium/potassium ATPase pump.This pump is the target of certain anion based inhibitors such as perchlorate, pertechnetate, and thiocyanate.