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Updated: Jul 26, 2026

A Rapid and Specific Microplate Assay for the Determination of Intra- and Extracellular Ascorbate in Cultured Cells
Published on: April 11, 2014
Glucose transporter isoforms GLUT1 and GLUT3 transport dehydroascorbic acid
1NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA.
Dehydroascorbic acid (DHA), a form of vitamin C, is transported into cells by glucose transporter isoforms GLUT1 and GLUT3. These transporters facilitate DHA uptake and its conversion to ascorbic acid (AA).
Area of Science:
- Cell biology
- Biochemistry
- Molecular transport
Background:
- Dehydroascorbic acid (DHA) is the oxidized form of ascorbic acid (AA), vitamin C.
- Cellular uptake of DHA is crucial for maintaining intracellular AA levels.
- The specific transporters mediating DHA uptake are not fully elucidated.
Purpose of the Study:
- To investigate the role of glucose transporter isoforms (GLUT1-5 and SGLT1) in the transport of DHA and AA.
- To characterize the kinetic properties and specificity of DHA transport mediated by glucose transporters.
Main Methods:
- Xenopus laevis oocyte expression system to study transporter function.
- Radiolabeled DHA and sugar uptake assays.
- High-performance liquid chromatography (HPLC) for DHA to AA conversion analysis.
- Inhibition studies using various hexoses and specific inhibitors (cytochalasin B, 4,6-O-ethylidene-alpha-glucose).
- Analysis of mutant GLUT1 and GLUT3 constructs.
- Overexpression studies in Chinese hamster ovary (CHO) cells.
Main Results:
- GLUT1 and GLUT3 significantly transported DHA, with apparent Km values of 1.1 ± 0.2 mM and 1.7 ± 0.3 mM, respectively.
- DHA was completely reduced to AA within oocytes expressing GLUT1 and GLUT3.
- GLUT2, GLUT4, GLUT5, and SGLT1 did not show significant DHA transport, and none of the tested isoforms transported AA.
- DHA transport via GLUT1 and GLUT3 was inhibited by glucose analogs but not by fructose or L-glucose.
- Inhibition studies with cytochalasin B and 4,6-O-ethylidene-alpha-glucose provided insights into the transport mechanism.
- Overexpression of GLUT1 or GLUT3 in CHO cells increased DHA and 2-deoxyglucose uptake.
Conclusions:
- GLUT1 and GLUT3 are the specific glucose transporter isoforms responsible for mediating DHA transport.
- The identified transporters facilitate the cellular uptake of DHA, leading to intracellular accumulation of ascorbic acid.
- These findings highlight a novel role for GLUT1 and GLUT3 in vitamin C metabolism.
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