Sodium-iodide symporter

Sodium-Iodide Symporter (NIS) is a protein that is primarily found in the thyroid gland. It plays a crucial role in the transport of iodide ions into the thyroid follicular cells, which is a necessary step in the synthesis of thyroid hormones.

Function

The primary function of the Sodium-Iodide Symporter is to transport iodide ions from the blood into the thyroid follicular cells. This process is essential for the production of thyroid hormones, which are critical for the regulation of the body's metabolism, growth, and development.

The transport process is an example of secondary active transport, where the energy for the transport of iodide ions is derived indirectly from ATP hydrolysis. The NIS protein uses the sodium gradient across the cell membrane, which is maintained by the sodium-potassium pump, to drive the transport of iodide ions into the cell.

Clinical Significance

Defects in the NIS protein can lead to congenital hypothyroidism, a condition characterized by low levels of thyroid hormones in the body. This can result in growth retardation, developmental delay, and other serious health problems.

The NIS protein is also a target for radioiodine therapy, a treatment for thyroid cancer. In this treatment, radioactive iodide is administered to the patient, and the NIS protein transports the radioactive iodide into the thyroid cancer cells, where it destroys them.

See Also

• Thyroid gland
• Thyroid hormones
• Congenital hypothyroidism
• Radioiodine therapy