GO:0033300 dehydroascorbic acid transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0033300 describes the molecular function that enables dehydroascorbate (DHA), the oxidized form of vitamin C, to cross biological membranes.
• DHA transport is distinct from ascorbate transport and is often mediated by facilitative glucose transporters (GLUTs) that also recognize DHA.
• Once inside cells, DHA is reduced back to ascorbate, maintaining the cellular antioxidant pool and supporting enzymatic reactions such as norepinephrine biosynthesis.
• Cytochrome b561 and its homologues participate in ascorbate-dependent electron transfer across membranes, functionally coupling DHA/ascorbate redox cycling to transport.
• Altered DHA transport and vitamin C homeostasis influence cancer cell survival, including breast cancer cells treated with tamoxifen.
• Experimental models for studying GO:0033300 include CRISPR knockout, point mutation, knock-in, and overexpression of candidate transporters in cell lines.
Description
GO:0033300, dehydroascorbic acid transmembrane transporter activity, is a molecular function term that describes the transfer of dehydroascorbate (DHA), the oxidized form of vitamin C, from one side of a membrane to the other. This activity is essential for vitamin C recycling and for maintaining intracellular redox balance, as DHA can be taken up by cells and then reduced to ascorbate. Unlike ascorbate, which is transported by sodium-dependent vitamin C transporters (SVCTs), DHA often enters cells through facilitative glucose transporters (GLUTs), linking vitamin C metabolism to glucose homeostasis. Researchers study GO:0033300 because DHA transport influences antioxidant defense, collagen synthesis, neurotransmitter production, and immune function. In endothelial cells, DHA transport is less sensitive to glucose competition than ascorbate transport, suggesting distinct regulatory roles. Cytochrome b561 family proteins, such as the tumor suppressor candidate 101F6, catalyze electron transfer reactions with ascorbate and monodehydroascorbate radical, functionally connecting to DHA/ascorbate cycling. In plants, tonoplast cytochrome b561 acts as a transmembrane ascorbate-dependent monodehydroascorbate reductase, highlighting evolutionary conservation of these redox transport mechanisms. Dysregulation of DHA transport has been implicated in cancer cell survival and response to therapy. For example, vitamin C suppresses tamoxifen-induced cell death in MCF-7 breast cancer cells, potentially through modulation of redox pathways involving DHA uptake. Understanding the molecular players and regulatory mechanisms of GO:0033300 is therefore critical for developing targeted interventions in cancer, neurodegeneration, and metabolic disorders.
dehydroascorbic acid transmembrane transporter activity At A Glance
| GO ID | GO:0033300 |
|---|---|
| GO term | dehydroascorbic acid transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | dehydroascorbate transporter activity; dehydroascorbic acid transporter activity |
| Major function | Enables transfer of dehydroascorbate across membranes |
| Substrate | Dehydroascorbate (DHA), the oxidized form of vitamin C |
| Cellular context | Plasma membrane, intracellular membranes, and organellar membranes |
| Related processes | Vitamin C recycling, redox homeostasis, antioxidant defense |
| Representative proteins | Glucose transporters (GLUTs), cytochrome b561 family proteins |
What Is GO:0033300?
According to the Gene Ontology, GO:0033300 enables the transfer of dehydroascorbate, chemically 5-(1,2-dihydroxyethyl)furan-2,3,4(5H)-trione, from one side of a membrane to the other. This activity is synonymous with dehydroascorbate transporter activity and dehydroascorbic acid transporter activity. It is a molecular function that facilitates the movement of the oxidized form of vitamin C across lipid bilayers, either through facilitated diffusion or secondary active transport mechanisms.
Why Is dehydroascorbic acid transmembrane transporter activity Important in Cell Biology?
GO:0033300 is important because it governs the cellular uptake and distribution of dehydroascorbate, a key intermediate in vitamin C metabolism. By controlling DHA transport, cells can regulate intracellular ascorbate levels, which are critical for antioxidant defense, collagen hydroxylation, neurotransmitter synthesis, and immune function. Dysregulated DHA transport has been linked to cancer progression and therapy resistance, as vitamin C can modulate cell death pathways in breast cancer cells. Moreover, DHA transport intersects with glucose metabolism because GLUTs can transport both glucose and DHA, making it relevant to diabetes and metabolic disorders. Understanding this activity at the molecular level provides insights into redox biology and offers potential therapeutic targets.
• Maintains intracellular ascorbate pools by enabling DHA uptake and subsequent reduction.
• Supports norepinephrine biosynthesis in chromaffin granules via ascorbate-dependent reactions.
• Links vitamin C homeostasis to glucose transport through shared GLUT carriers.
• Modulates cancer cell survival, as vitamin C can suppress tamoxifen-induced death in MCF-7 cells.
• Involves cytochrome b561 homologues that catalyze electron transfer with ascorbate and monodehydroascorbate radical.
• Shows evolutionary conservation, with plant tonoplast cytochrome b561 functioning as a transmembrane ascorbate-dependent reductase.
• Impacts endothelial cell biology, where DHA transport is less affected by glucose competition than ascorbate transport.
• Provides a target for studying redox-related diseases including cancer, neurodegeneration, and metabolic syndrome.
• Enables experimental dissection of transport kinetics using radiolabeled DHA and competition assays.
• Offers opportunities for CRISPR-based functional genomics of candidate transporters.
Molecular Mechanism of dehydroascorbic acid transmembrane transporter activity
Substrate recognition and binding
In simple terms: The transporter must first recognize and bind dehydroascorbate, the oxidized form of vitamin C.
Dehydroascorbate (DHA) is a polar molecule that requires specific transporters to cross lipid bilayers. Facilitative glucose transporters (GLUTs) can recognize DHA as a substrate, although with lower affinity than glucose. This binding is competitive, as increasing glucose concentrations can inhibit DHA transport in some cell types, but endothelial cells show moderate DHA transport even under high glucose. The molecular determinants of DHA recognition likely involve hydrogen bonding and steric complementarity within the transporter's substrate pocket, though precise structural data remain limited.
Translocation across the membrane
In simple terms: After binding, the transporter undergoes conformational changes to move DHA across the membrane.
Translocation of DHA occurs via facilitated diffusion or secondary active transport, depending on the transporter. For GLUT-mediated transport, an alternating access mechanism is proposed, where the transporter switches between outward-facing and inward-facing conformations. This process is driven by concentration gradients and does not require direct ATP hydrolysis. In contrast, some transporters may couple DHA movement to ion gradients, but evidence for such coupling in mammalian systems is less established.
Reduction and recycling of ascorbate
In simple terms: Once inside the cell, DHA is converted back to ascorbate to restore its antioxidant function.
After transport, DHA is rapidly reduced to ascorbate by intracellular reductases, including glutathione-dependent and NADPH-dependent enzymes. This reduction maintains the cellular ascorbate pool and supports enzymatic reactions such as norepinephrine biosynthesis in chromaffin granules. Cytochrome b561 proteins facilitate electron transfer across membranes using ascorbate as an electron donor, generating monodehydroascorbate radical, which can be further reduced. In plants, tonoplast cytochrome b561 acts as a transmembrane ascorbate-dependent monodehydroascorbate reductase, demonstrating a conserved redox cycling mechanism.
Regulation by glucose and metabolic state
In simple terms: Glucose levels and cellular metabolism can influence how much DHA is transported.
DHA transport via GLUTs is sensitive to glucose concentrations, as glucose competes for the same binding site. In aortic endothelial cells, DHA transport is moderately controlled and less affected by glucose competition compared to ascorbate transport, suggesting distinct regulatory mechanisms. This interplay links vitamin C homeostasis to glucose metabolism, with implications for diabetes and metabolic disorders. Additionally, cell cycle status and oxidative stress can modulate transporter expression and activity, though specific pathways require further investigation.
Electron transfer and redox coupling
In simple terms: Electron transfer reactions connect DHA transport to cellular redox networks.
Cytochrome b561 homologues, such as the candidate tumor suppressor 101F6, catalyze electron transfer between ascorbate and monodehydroascorbate radical. These reactions are integral to regenerating ascorbate from DHA and maintaining redox balance. The 101F6 protein exhibits electron transfer activity with ascorbate, supporting a role in redox cycling that may indirectly influence DHA transport by maintaining gradients. Similarly, plant tonoplast cytochrome b561 functions as a monodehydroascorbate reductase, highlighting the evolutionary importance of these electron transfer pathways.
Key Genes Involved in GO:0033300 dehydroascorbic acid transmembrane transporter activity
The following genes and proteins are functionally associated with dehydroascorbic acid transmembrane transporter activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC2A1 (GLUT1) | Facilitative glucose transporter that can also transport DHA | Mediates DHA uptake in many cell types; target for metabolic studies |
| SLC2A3 (GLUT3) | Neuronal glucose transporter with DHA transport capacity | Potential role in brain vitamin C homeostasis |
| SLC2A4 (GLUT4) | Insulin-responsive glucose transporter | May contribute to DHA transport in muscle and adipose tissue |
| CYB561 | Cytochrome b561, ascorbate-dependent electron transfer | Facilitates redox cycling linked to DHA/ascorbate |
| CYB561D2 (101F6) | Cytochrome b561 homologue, tumor suppressor candidate | Electron transfer with ascorbate and monodehydroascorbate radical |
| SLC23A1 (SVCT1) | Sodium-dependent vitamin C transporter 1 | Transports ascorbate, not DHA, but maintains vitamin C pool |
| SLC23A2 (SVCT2) | Sodium-dependent vitamin C transporter 2 | Transports ascorbate in neurons and other tissues |
| GULO | L-gulonolactone oxidase (functional in some species) | Involved in ascorbate synthesis; not present in humans |
| RGN (SMP30) | Regucalcin, gluconolactonase | Participates in ascorbate biosynthesis in some organisms |
| GSR | Glutathione reductase | Supports regeneration of ascorbate via glutathione cycle |
| TXNRD1 | Thioredoxin reductase 1 | Contributes to redox homeostasis affecting DHA/ascorbate balance |
| NQO1 | NAD(P)H quinone dehydrogenase 1 | May reduce dehydroascorbate to ascorbate |
| AKR1A1 | Aldo-keto reductase family 1 member A1 | Has dehydroascorbate reductase activity |
| PRDX1 | Peroxiredoxin 1 | Antioxidant enzyme influencing redox state |
| SOD1 | Superoxide dismutase 1 | Cytosolic antioxidant affecting DHA levels |
| CAT | Catalase | Peroxisomal antioxidant linked to redox balance |
| GPX1 | Glutathione peroxidase 1 | Reduces hydrogen peroxide, impacting ascorbate pool |
| G6PD | Glucose-6-phosphate dehydrogenase | Generates NADPH for ascorbate regeneration |
How Is dehydroascorbic acid transmembrane transporter activity Regulated?
The activity of dehydroascorbic acid transmembrane transporters is regulated at multiple levels. Glucose availability directly competes with DHA for GLUT-mediated transport, as shown in endothelial cells where increasing glucose concentrations reduce DHA uptake. Cell cycle status also influences transport, with moderately controlled DHA transport observed against slowdown of the cell cycle. Oxidative stress can upregulate antioxidant systems that regenerate ascorbate from DHA, indirectly affecting transport gradients. Additionally, cytochrome b561 proteins are regulated by ascorbate availability and redox state, modulating electron transfer reactions that are coupled to DHA/ascorbate cycling. Hormonal and metabolic signals, such as insulin, may influence GLUT4 translocation and thus DHA transport in insulin-sensitive tissues, though direct evidence is limited.
dehydroascorbic acid transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC2A1 (GLUT1) | Cancer metabolism, glucose transport | CRISPR knockout in MCF-7 breast cancer cells |
| CYB561D2 (101F6) | Tumor suppression, redox regulation | Overexpression in cancer cell lines |
| SLC2A4 (GLUT4) | Insulin resistance, diabetes | Knockout in skeletal muscle cells |
| CYB561 | Neurodegeneration, neurotransmitter synthesis | Knock-in of tagged CYB561 in neuronal cells |
| SLC23A2 (SVCT2) | Vitamin C deficiency, brain function | Point mutation in neuronal cell lines |
Cancer and Chemoresistance
Vitamin C and its oxidized form DHA influence cancer cell survival and response to therapy. In MCF-7 human breast cancer cells, vitamin C suppresses tamoxifen-induced cell death, suggesting that DHA transport and subsequent redox modulation can protect cancer cells from chemotherapy. This protective effect may involve the reduction of DHA to ascorbate, which scavenges reactive oxygen species and alters apoptotic signaling. Targeting DHA transporters could therefore sensitize cancer cells to therapy, but further research is needed to identify specific transporters in different cancer types.
Neurodegeneration and Neurotransmitter Synthesis
DHA transport is critical for maintaining ascorbate levels in the brain, where vitamin C acts as a neuromodulator and antioxidant. In chromaffin granules, ascorbate is required for norepinephrine biosynthesis, and semidehydroascorbic acid serves as an intermediate. Cytochrome b561 proteins, which are enriched in neuroendocrine tissues, facilitate electron transfer for ascorbate regeneration. Impaired DHA transport could therefore contribute to neurodegenerative processes by reducing ascorbate availability, though direct evidence linking GO:0033300 to specific neurodegenerative diseases is still emerging.
Metabolic Disorders and Endothelial Dysfunction
Competition between glucose and DHA for GLUT-mediated transport links vitamin C homeostasis to glucose metabolism. In aortic endothelial cells, DHA transport is less sensitive to glucose competition than ascorbate transport, but high glucose can still impair DHA uptake. This may contribute to endothelial dysfunction in diabetes, where reduced intracellular ascorbate exacerbates oxidative stress. Understanding the interplay between glucose and DHA transport could inform therapeutic strategies for diabetic complications.
From dehydroascorbic acid transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does knockout of SLC2A1 reduce DHA transport? | CRISPR knockout in HeLa or MCF-7 cells |
| Does a point mutation in GLUT1 alter DHA affinity? | CRISPR point mutation knock-in in HEK293T cells |
| Can tagged CYB561 be used to track DHA-dependent electron transfer? | Knock-in of fluorescent tag at endogenous CYB561 locus |
| Does overexpression of 101F6 enhance ascorbate regeneration? | Overexpression in cancer cell lines |
| Does glucose competition affect DHA transport in endothelial cells? | CRISPR knockout of GLUTs in aortic endothelial cells |
| Does DHA transport modulate tamoxifen sensitivity? | Overexpression or knockout in MCF-7 cells |
How to Study the dehydroascorbic acid transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled DHA uptake | Transport kinetics and substrate specificity | Comparing wild-type and knockout cells |
| Electron transfer assay | Cytochrome b561 activity with ascorbate | Characterizing redox cycling proteins |
| CRISPR knockout screening | Genes affecting DHA transport | Identifying novel transporters |
| Metabolomics (LC-MS) | Intracellular ascorbate and DHA levels | Assessing transport and reduction |
| Fluorescent redox sensors | Cellular redox state | Live-cell imaging of DHA effects |
| Western blotting | Transporter protein expression | Validating CRISPR knockouts |
| qRT-PCR | mRNA levels of candidate transporters | Gene expression profiling |
| Competition assay with glucose | Substrate preference of GLUTs | Studying glucose-DHA interplay |
Transport Assays with Radiolabeled DHA
Radiolabeled dehydroascorbate (e.g., 14C-DHA) is used to measure transport kinetics in cultured cells. Cells are incubated with labeled DHA, and uptake is quantified by scintillation counting. Competition assays with glucose or other substrates can reveal transporter specificity. This method is suitable for comparing wild-type and CRISPR-modified cells to assess the contribution of specific transporters.
Electrophysiology and Electron Transfer Measurements
Cytochrome b561 proteins can be studied using electrophysiological techniques or spectrophotometric assays to measure electron transfer between ascorbate and monodehydroascorbate radical. These methods provide real-time kinetic data on redox reactions coupled to DHA/ascorbate cycling. Plant tonoplast cytochrome b561 has been characterized using similar approaches.
CRISPR Screening and Functional Genomics
Genome-wide CRISPR knockout or activation screens can identify genes that regulate DHA transport. Cells are exposed to DHA under selective conditions, and sgRNA enrichment is analyzed by next-generation sequencing. This approach can uncover novel transporters or regulatory factors beyond known GLUTs.
Metabolomics and Redox Profiling
Mass spectrometry-based metabolomics can quantify intracellular ascorbate and DHA levels, providing a readout of transport activity. Redox profiling, including glutathione and reactive oxygen species measurements, complements transport assays to assess downstream effects.
How CRISPR Can Be Used to Study GO:0033300 dehydroascorbic acid transmembrane transporter activity
Knockout
CRISPR knockout of candidate DHA transporters such as SLC2A1 (GLUT1) can abolish or reduce DHA uptake, allowing researchers to determine which transporters are essential in a given cell type. Knockout cells can be compared to wild-type controls in radiolabeled DHA transport assays. This approach is particularly useful for dissecting redundant transporter families.
Point Mutation
CRISPR point mutation can introduce specific amino acid substitutions in transporter genes to test their role in DHA binding and translocation. For example, mutating residues in the substrate pocket of GLUT1 can alter affinity for DHA versus glucose. Such models help define structure-function relationships.
Knock-in
Knock-in of epitope tags or fluorescent proteins at endogenous loci enables real-time tracking of transporter localization and dynamics. Tagged CYB561 or GLUT1 can be used to study membrane trafficking and interaction partners in live cells. This approach preserves native regulatory elements.
Overexpression
Overexpression of candidate transporters or redox enzymes such as 101F6 can enhance DHA transport or ascorbate regeneration, providing gain-of-function models. These models are useful for testing whether increased DHA uptake protects cells from oxidative stress or alters drug sensitivity.
How EDITGENE Supports dehydroascorbic acid transmembrane transporter activity Research
Researchers studying dehydroascorbic acid transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in DHA uptake, redox balance, or disease phenotypes. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models, enabling functional validation of transporters and associated proteins.
Contact EDITGENE today to design your custom CRISPR model for dehydroascorbic acid transmembrane transporter activity research.
Frequently Asked Questions About dehydroascorbic acid transmembrane transporter activity
What is dehydroascorbic acid transmembrane transporter activity?
It is a molecular function (GO:0033300) that enables the transfer of dehydroascorbate, the oxidized form of vitamin C, across biological membranes.
What genes are involved in dehydroascorbic acid transport?
Genes encoding facilitative glucose transporters (e.g., SLC2A1, SLC2A3, SLC2A4) and cytochrome b561 family members (e.g., CYB561, CYB561D2) are implicated in DHA transport and redox cycling.
How is dehydroascorbic acid transported into cells?
DHA is primarily transported via facilitative glucose transporters (GLUTs) through facilitated diffusion, and once inside, it is reduced to ascorbate.
What is the difference between ascorbate and dehydroascorbate transport?
Ascorbate is transported by sodium-dependent vitamin C transporters (SVCTs), while dehydroascorbate uses glucose transporters (GLUTs) and is not sodium-dependent.
Why is dehydroascorbic acid transport important in cancer?
Vitamin C and DHA can modulate cancer cell survival; in MCF-7 breast cancer cells, vitamin C suppresses tamoxifen-induced cell death, highlighting a role in chemoresistance.
Which diseases are linked to dehydroascorbic acid transport?
Dysregulated DHA transport has been associated with cancer, neurodegeneration, and metabolic disorders such as diabetes, though direct causal links require further study.
How can I study dehydroascorbic acid transmembrane transporter activity?
Common methods include radiolabeled DHA uptake assays, CRISPR knockout of candidate transporters, and metabolomics to measure ascorbate levels.
What is the role of cytochrome b561 in DHA transport?
Cytochrome b561 proteins facilitate electron transfer between ascorbate and monodehydroascorbate radical, supporting redox cycling that is functionally linked to DHA/ascorbate homeostasis.
Can CRISPR be used to study DHA transporters?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models enable precise functional dissection of candidate transporters in cell lines.
What are the synonyms for GO:0033300?
The synonyms are dehydroascorbate transporter activity and dehydroascorbic acid transporter activity.
Conclusion
GO:0033300, dehydroascorbic acid transmembrane transporter activity, is a critical molecular function for vitamin C homeostasis and redox biology. It enables DHA uptake through facilitative glucose transporters and is coupled to ascorbate regeneration via cytochrome b561-mediated electron transfer. Dysregulation of this activity has implications for cancer, neurodegeneration, and metabolic disorders, making it a compelling target for further research. Advances in CRISPR-based models and functional genomics will accelerate the discovery of novel transporters and regulatory mechanisms, ultimately informing therapeutic strategies.
References
- 1. Dhariwal KR et al.. 1991. Semidehydroascorbic acid as an intermediate in norepinephrine biosynthesis in chromaffin granules.. J Biol Chem 266(20):12908-14 PMID: 1649168
- 2. Gradogna A et al.. 2023. Tonoplast cytochrome b561 is a transmembrane ascorbate-dependent monodehydroascorbate reductase: functional characterization of electron currents in plant vacuoles.. New Phytol 238(5):1957-1971 PMID: 36806214
- 3. Subramani T et al.. 2014. Vitamin C suppresses cell death in MCF-7 human breast cancer cells induced by tamoxifen.. J Cell Mol Med 18(2):305-13 PMID: 24266867
- 4. Saitoh Y et al.. 1997. Moderately controlled transport of ascorbate into aortic endothelial cells against slowdown of the cell cycle, decreasing of the concentration or increasing of coexistent glucose as compared with dehydroascorbate.. Mol Cell Biochem 173(1-2):43-50 PMID: 9278253
- 5. Recuenco MC et al.. 2013. Electron transfer reactions of candidate tumor suppressor 101F6 protein, a cytochrome b561 homologue, with ascorbate and monodehydroascorbate radical.. Biochemistry 52(21):3660-8 PMID: 23641721
