What is the function of sodium iodide Symporter?
What is the function of sodium iodide Symporter?
The sodium iodide symporter (NIS) is responsible for thyroidal, salivary, gastric, intestinal and mammary iodide uptake. It was first cloned from the rat in 1996 and shortly thereafter from human and mouse tissue.
Is the sodium iodide Symporter a secondary active transport?
As its name indicates, the sodium-iodide symporter simultaneously transports both Na+ and I- ions from extracellular fluid (i.e. blood) into the thryoid epithelial cell. This process is an example of secondard active transport.
Which of the following is the transporter responsible for the transport of iodine into the thyroid cells against the concentration gradient?
As illustrated in Figure 1, the NIS (SLC5A5), a member of the solute carrier family 5, located at the basolateral plasma membrane of the thyroid follicular cells actively transports iodide into the thyroid using the electrochemical gradient generated by the Na,K-ATPase [9-11].
What is NIS in physiology?
Abstract. The Na+/I− symporter (NIS) is the plasma membrane glycoprotein that mediates active I− transport in the thyroid and other tissues, such as salivary glands, stomach, lactating breast, and small intestine.
What is the effect of Deiodinases on thyroid hormone function?
Deiodinases expressed in peripheral tissues remove iodine from thyroid hormones, converting T4 to T3, an important action in increasing hormone potency, and further removing iodine to inactivate the hormones completely.
Where is sodium iodide Symporter found?
The human sodium iodide symporter (hNIS) gene is naturally present in humans with fairly restricted tissue expression (thyroid, stomach, salivary, and lactating mammary glands).
What kind of transport is necessary to transport iodine into a cell?
Iodine uptake is a result of an active transport mechanism mediated by the NIS protein, which is found in the basolateral membrane of thyroid follicular cells. As a result of this active transport, iodide concentration inside follicular cells of thyroid tissue is 20 to 50 times higher than in the plasma.
Is Symport active or passive transport?
active transport
Symporters and antiporters are involved in active transport. Antiporters transport molecules in opposite directions, while symporters transport molecules in the same direction.
Where is sodium iodide Symporter?
What is an example of Symport?
Symport is a form of active transport. It uses the downhill movement of solute species from high concentration to lower for the movement of other molecules uphill from low to high concentration, which takes place against the electrochemical gradient. An example is the glucose symporter SGLT1.
What inhibits peripheral conversion from T4 to T3?
Propylthiouracil (PTU, Propyl-Thyracil) DOC that inhibits synthesis of TH by preventing organification and trapping of iodide to iodine and by inhibiting coupling of iodotyrosines; also inhibits peripheral conversion of T4 to T3, an important component of management.
What inhibits T4 to T3?
Amiodarone inhibits T4 to T3 conversion and alpha-glycerophosphate dehydrogenase and malic enzyme levels in rat liver. Horm Metab Res.
What stimulates thyroid hormone release?
Thyroid-releasing hormone (TRH) from the hypothalamus stimulates TSH from the pituitary, which stimulates thyroid hormone release.
How does iodide enter a cell?
The transport of iodide across the cell membrane is driven by the electrochemical gradient of sodium (the intracellular concentration of sodium is approximately 12 mM and extracellular concentration 140 mM).
How is iodide transported in the body?
The iodide within the follicular cell moves towards the apical surface of the plasma membrane, to enter into the follicular lumen; this transport by a sodium independent iodide/chloride transporter called pendrin.
What type of transport is symport?
cotransporter
A symporter is an integral membrane protein that is involved in the transport of two different molecules across the cell membrane in the same direction. The symporter works in the plasma membrane and molecules are transported across the cell membrane at the same time, and is, therefore, a type of cotransporter.
What is the enzyme that converts T4 to T3?
T4 is converted into T3, the active form of thyroid hormone, by two enzymes called deiodinases. People with hypothyroidism are treated with a synthetic T4 hormone, which the enzymes convert to T3.
What is the sodium iodide symporter (NIS)?
Expression of the sodium iodide symporter (NIS) is required for efficient iodide uptake in thyroid and lactating breast. Since most differentiated thyroid cancer expresses NIS, β-emitting radioactive iodide is routinely utilized to target remnant thyroid cancer and metastasis after total thyroidectomy.
What is NIS-mediated iodide accumulation in the thyroid?
In addition to its key function in thyroid physiology, NIS-mediated iodide accumulation allows diagnostic thyroid scintigraphy as well as effective therapeutic application of radioiodine in benign and malignant thyroid disease.
Does iodide therapy affect NIS function?
EFFECT OF IODIDE THERAPY ON NIS FUNCTION Although the function of NIS is to mediate iodide uptake in thyroid tissue, pre-treatment with iodide has been found to have rather complex paradoxical effects on NIS expression and function. Inhibition of thyroid function following administration of large doses of iodide is well-known.
What is the role of sodium iodide in the thyroid gland?
The ability of the thyroid gland to transport and concentrate iodide from blood is absolutely necessary for the synthesis of thyroid hormones. The key player in this process is the sodium-iodide symporter, an integral membrane protein that resides in the basolateral membrane of thyroid epithelial cells.
