dehydroascorbic acid transport

Definition

Target type: biologicalprocess

The directed movement of dehydroascorbate into, out of or within a cell, or between cells, by means of some agent such as a transporter or pore. Dehydroascorbate, 5-(1,2-dihydroxyethyl)furan-2,3,4(5H)-trione, is an oxidized form of vitamin C. [GOC:sl]

Dehydroascorbic acid (DHA), the oxidized form of vitamin C, is transported across biological membranes via specialized transport proteins. The primary transporter responsible for DHA uptake in various tissues, including the liver, kidney, and intestines, is the **sodium-dependent vitamin C transporter 2 (SVCT2)**.

SVCT2 is a transmembrane protein that facilitates the co-transport of DHA with sodium ions. The mechanism involves the following steps:

1. **DHA binds to SVCT2 on the extracellular side of the membrane.** This binding event triggers a conformational change in the transporter, allowing sodium ions to bind to a separate site.

2. **Sodium ions bind to SVCT2.** The simultaneous binding of DHA and sodium ions initiates the transport process.

3. **SVCT2 undergoes a conformational change, translocating DHA and sodium ions across the membrane.** This movement is driven by the electrochemical gradient of sodium ions, which flows down its concentration gradient from the extracellular space to the intracellular compartment.

4. **DHA is released into the intracellular space.** The transporter returns to its original conformation, ready for another transport cycle.

The transport of DHA by SVCT2 is essential for maintaining intracellular vitamin C levels. DHA can be readily converted back to its reduced form, ascorbic acid, by cellular reductases. This process ensures a continuous supply of vitamin C, which is crucial for various biological functions, including collagen synthesis, antioxidant defense, and immune system regulation.

In addition to SVCT2, other transporters may contribute to DHA transport in specific tissues or under specific conditions. For instance, **glucose transporters (GLUTs)**, particularly GLUT1 and GLUT3, have been shown to transport DHA to a lesser extent. However, their role in DHA uptake is generally considered less significant compared to SVCT2.

Furthermore, DHA transport can also be influenced by factors such as pH, temperature, and the presence of other molecules. The precise mechanisms and regulation of DHA transport are still under investigation, but the current understanding highlights the importance of SVCT2 as the primary transporter for this essential nutrient.'
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Proteins (5)

Compounds (27)