The sodium-iodide symporter.

The sodium-iodide symporter (NIS) is an intrinsic plasma membrane protein that mediates active transport of iodide in the thyroid gland and several other extra-thyroidal tissues. This activity has been utilized for many years for imaging the thyroid gland and for treatment of thyroid disease both benign and malignant. Cloning and characterization of NIS has more recently allowed research into its use in non-thyroidal cancers through gene transfer for both diagnosis and treatment.