Deiodinázok

Deiodinázok are a family of enzymes that play a crucial role in thyroid hormone metabolism. These enzymes are responsible for catalyzing the removal of iodine atoms from thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3). This process is essential for regulating the body's metabolic rate and for ensuring that the appropriate levels of active thyroid hormone are present in different tissues and at different times.

There are three main types of deiodinases: deiodinase 1 (D1), deiodinase 2 (D2), and deiodinase 3 (D3). Each type has a distinct tissue distribution and substrate preference, leading to different physiological functions. D1 is found mainly in the liver, kidney, and thyroid gland, and it can activate T4 into T3 or inactivate T3. D2 is predominantly located in the brain, pituitary gland, and brown adipose tissue, and it primarily activates T4 into the more potent T3. D3 is found in a variety of tissues, including the brain, placenta, and skin, and it acts to inactivate both T4 and T3, thereby reducing thyroid hormone activity.

The activity of deiodinases is tightly regulated by various factors, including thyroid hormone levels themselves, selenium, and other cellular signals. This regulation ensures that thyroid hormone levels are precisely controlled to meet the body's needs. Defects in deiodinase function can lead to thyroid hormone resistance or other metabolic disorders. Understanding the role and regulation of deiodinases is therefore important for comprehending thyroid hormone physiology and for developing treatments for thyroid-related diseases.