sodium/iodide symporter is iodide brought into follicular cells from the bloodstream in the thyroid glands. The symporter an integral plasma membrane glycoprotein that mediates active transport into the thyroid follicular cells. Sodium iodide symporter (NIS) is responsible for thyroidal,salivary, gastric, intestinal and mammary iodide uptake.The transport from the blood stream to the collid is made possible by selective targeting of NIs to the basolateral membrane