GO:0015210 uracil transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015210 (uracil transmembrane transporter activity) describes the molecular function that enables transfer of uracil, 2,4-dioxopyrimidine, across a membrane.
• The structural basis of uracil transport was revealed by the crystal structure of the bacterial uracil:proton symporter UraA, which established the elevator-type alternating-access mechanism for the SLC4/23/26 transporter superfamily.
• Human equilibrative nucleoside transporter 1 (SLC29A1/hENT1) also transports uracil and other nucleobases, showing that uracil transmembrane transport is not restricted to a single protein family.
• Uracil transport and pyrimidine salvage are mechanistically linked to 5-fluorouracil (5-FU) sensitivity, making this activity relevant to chemotherapy response in colorectal cancer.
• Uracil transmembrane transporter activity can be studied with transport assays, radiolabeled flux, electrophysiology, and structural biology, complemented by CRISPR knockout and point-mutation models.
• The term is a molecular_function in the Gene Ontology and is distinct from nucleoside transport, although some transporters show overlapping substrate specificity.
Description
GO:0015210, uracil transmembrane transporter activity, is a Gene Ontology molecular_function term defined as enabling the transfer of uracil, 2,4-dioxopyrimidine, from one side of a membrane to the other. Uracil is a pyrimidine nucleobase that is central to RNA metabolism and to pyrimidine salvage pathways, and its movement across biological membranes is therefore a fundamental cellular process. The term is used by researchers to annotate proteins that mediate uracil flux, including proton-coupled symporters and members of the equilibrative nucleoside transporter family. The best-characterized structural model for uracil transmembrane transport comes from the bacterial uracil:proton symporter UraA, whose crystal structure revealed an elevator-type alternating-access mechanism and provided a template for understanding the SLC4/23/26 transporter superfamily. In humans, equilibrative nucleoside transporter 1 (SLC29A1, hENT1) has been shown to transport uracil and other nucleobases, indicating that uracil transmembrane transporter activity is distributed across multiple transporter families. Understanding GO:0015210 matters because uracil transport intersects with nucleotide metabolism, RNA synthesis, and drug response. For example, TMEM97 knockdown has been reported to inhibit 5-fluorouracil resistance by regulating epithelial-mesenchymal transition and ABC transporter expression via inactivation of the Akt/mTOR pathway in 5-fluorouracil-resistant colorectal cancer cells. This makes uracil transmembrane transporter activity a relevant functional annotation for cancer pharmacology and for studies of pyrimidine salvage.
uracil transmembrane transporter activity At A Glance
| GO ID | GO:0015210 |
|---|---|
| GO term | uracil transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | uracil/uridine permease activity |
| Major function | Enables transfer of uracil, 2,4-dioxopyrimidine, from one side of a membrane to the other |
| Structural paradigm | UraA uracil:proton symporter, elevator-type alternating-access mechanism |
| Human example | SLC29A1 (hENT1) transports uracil and other nucleobases |
| Related superfamily | SLC4/23/26 transporters |
| Disease relevance | 5-fluorouracil resistance in colorectal cancer |
What Is GO:0015210?
In plain terms, GO:0015210 describes the job of a membrane protein that moves uracil from one side of a membrane to the other. The official Gene Ontology definition states that this activity enables the transfer of uracil, 2,4-dioxopyrimidine, from one side of a membrane to the other. The synonym uracil/uridine permease activity reflects the historical observation that some permeases can handle both uracil and uridine. This is a molecular_function term, so it describes what a protein does at the molecular level rather than where it is located or which pathway it belongs to.
Why Is uracil transmembrane transporter activity Important in Cell Biology?
Uracil transmembrane transporter activity is important because uracil is a key pyrimidine nucleobase whose intracellular availability affects RNA synthesis, pyrimidine salvage, and the response to fluoropyrimidine drugs. The structural and mechanistic characterization of UraA established a general framework for understanding how uracil and related solutes cross membranes, and this framework extends to the SLC4/23/26 transporter superfamily. In human cells, hENT1-mediated nucleobase transport demonstrates that uracil flux can occur through transporters originally classified as nucleoside carriers. Because uracil transport influences 5-fluorouracil handling, this activity is also relevant to cancer therapy, where changes in transporter expression or function can alter drug sensitivity.
• Defines a specific molecular function that can be used to annotate genes and proteins in genome-scale analyses.
• Provides a structural template for understanding elevator-type transport in the SLC4/23/26 superfamily.
• Links pyrimidine salvage and RNA metabolism to membrane transport.
• Explains how uracil can enter cells through transporters such as hENT1/SLC29A1.
• Connects transporter activity to 5-fluorouracil resistance in colorectal cancer models.
• Supports drug discovery efforts targeting nucleobase and nucleoside transport.
• Helps interpret transport assays and radiolabeled flux experiments.
• Guides CRISPR knockout and point-mutation studies of candidate transporters.
• Clarifies the distinction between uracil transport and uric acid-xanthine transport by related transporters.
• Provides a functional annotation for comparative genomics of microbial and human transporters.
Molecular Mechanism of uracil transmembrane transporter activity
Substrate recognition and binding
In simple terms: The transporter first grabs uracil from one side of the membrane.
Uracil transmembrane transporter activity begins with substrate recognition. The bacterial uracil:proton symporter UraA binds uracil with high specificity, and its crystal structure revealed the architecture of the substrate-binding site. The dimeric structure of UraA further provided mechanistic insights into how the binding site is organized and how it relates to the SLC4/23/26 transporters. In human cells, hENT1 (SLC29A1) can also recognize uracil and other nucleobases, indicating that substrate recognition is not limited to a single structural family.
Alternating-access conformational cycle
In simple terms: The transporter changes shape to carry uracil across the membrane.
After binding, the transporter undergoes conformational changes that move uracil across the lipid bilayer. The UraA structure established an elevator-type alternating-access mechanism, in which a transport domain moves relative to a scaffold domain to expose the substrate to opposite sides of the membrane. The dimeric UraA structure extended this model and linked it to the broader SLC4/23/26 transporter superfamily. This mechanism ensures that uracil is transferred from one side of the membrane to the other without forming a continuous open channel.
Proton coupling and energetics
In simple terms: Some uracil transporters use protons to power the transport.
UraA functions as a uracil:proton symporter, coupling uracil movement to proton translocation. This coupling provides the energetic driving force for concentrative uracil uptake. The structural data on UraA and its dimeric form provide a framework for understanding how proton coupling is achieved in this transporter family. In contrast, human hENT1-mediated nucleobase transport is not necessarily proton-coupled, illustrating mechanistic diversity among uracil transporters.
Specificity and related transporters
In simple terms: Some transporters are picky, while others accept several similar molecules.
Substrate specificity varies among transporters annotated with uracil transmembrane transporter activity. UraA is a specific uracil:proton symporter, whereas hENT1 can transport uracil and other nucleobases. Studies of the related fungal transporter UapA showed that a single substitution, F569S, converts a specific uric acid-xanthine transporter into a broad-specificity transporter for purine-related solutes, demonstrating that specificity can be altered by point mutations. These findings highlight the importance of experimental validation when assigning transporter function.
Regulation and cellular context
In simple terms: Cells can adjust how much uracil they take up depending on their needs.
Uracil transmembrane transporter activity operates within a cellular context that includes nucleotide metabolism and drug response. In 5-fluorouracil-resistant colorectal cancer cells, TMEM97 knockdown inhibited resistance by regulating epithelial-mesenchymal transition and ABC transporter expression via inactivation of the Akt/mTOR pathway. This suggests that transporter activity and drug efflux systems can be coordinately regulated. Inhibitors of monocarboxylate transporters 1 and 4 have also been explored as potential therapeutics for solid tumours, illustrating the broader pharmacological interest in solute carrier transporters.
Key Genes Involved in GO:0015210 uracil transmembrane transporter activity
The following genes and proteins are directly or functionally linked to uracil transmembrane transporter activity and its cellular context.
| Gene | Major Role | Research Relevance |
|---|---|---|
| uraA (bacterial) | Uracil:proton symporter | Structural paradigm for uracil transport; elevator-type alternating-access mechanism |
| SLC29A1 (hENT1) | Equilibrative nucleoside transporter that also transports uracil | Human example of nucleobase transport by a nucleoside transporter |
| UapA (fungal) | Uric acid-xanthine transporter | Model for substrate specificity changes via point mutation (F569S) |
| TMEM97 | Regulates EMT and ABC transporter expression | Linked to 5-fluorouracil resistance via Akt/mTOR pathway |
| SLC16A1 (MCT1) | Monocarboxylate transporter | Target for solid tumour therapeutics; context for solute carrier pharmacology |
| SLC16A3 (MCT4) | Monocarboxylate transporter | Target for solid tumour therapeutics; context for solute carrier pharmacology |
| SLC4 family members | Bicarbonate transporters related to UraA fold | Structural relationship to SLC4/23/26 superfamily |
| SLC23 family members | Nucleobase/nucleoside transporters | Structural relationship to SLC4/23/26 superfamily |
| SLC26 family members | Anion transporters related to UraA fold | Structural relationship to SLC4/23/26 superfamily |
| STIM1 | Calcium sensor | Reported as critical for enamel maturation alongside SLC24A4 |
| SLC24A4 | Sodium/potassium/calcium exchanger | Reported as critical for enamel maturation |
| ABC transporters | Drug efflux pumps | Regulated in 5-FU-resistant colorectal cancer cells |
| Akt | Kinase in survival signaling | Inactivated upon TMEM97 knockdown in 5-FU-resistant cells |
| mTOR | Kinase in growth signaling | Inactivated upon TMEM97 knockdown in 5-FU-resistant cells |
| Cyclopropyl-uracil targets | Herbicide targets | Novel cyclopropyl-uracil derivatives as potent herbicides |
| Pyrimidine salvage enzymes | Recycle uracil into nucleotides | Functional context for uracil transport |
How Is uracil transmembrane transporter activity Regulated?
Uracil transmembrane transporter activity is regulated at multiple levels. At the transporter level, substrate specificity can be altered by point mutations, as shown for UapA F569S, which converts a specific uric acid-xanthine transporter into a broad-specificity transporter for purine-related solutes. At the cellular level, signaling pathways such as Akt/mTOR can influence the expression of transporters and drug efflux systems; TMEM97 knockdown inhibited 5-fluorouracil resistance by regulating epithelial-mesenchymal transition and ABC transporter expression via inactivating the Akt/mTOR pathway in 5-fluorouracil-resistant colorectal cancer cells. In addition, the structural transitions of UraA during its transport cycle are intrinsically regulated by proton coupling and the alternating-access mechanism.
uracil transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| TMEM97 | 5-fluorouracil resistance in colorectal cancer | TMEM97 knockdown in 5-FU-resistant colorectal cancer cell lines |
| SLC29A1 (hENT1) | Nucleobase transport in human cells | Transport assays in hENT1-expressing cell models |
| SLC16A1 (MCT1) | Solid tumour metabolism | MCT1 inhibitor treatment in cancer cell lines |
| SLC16A3 (MCT4) | Solid tumour metabolism | MCT4 inhibitor treatment in cancer cell lines |
| STIM1 / SLC24A4 | Enamel maturation | Genetic and functional studies in enamel-forming cells |
Colorectal cancer and 5-fluorouracil resistance
Uracil transmembrane transporter activity is relevant to colorectal cancer because uracil metabolism intersects with 5-fluorouracil (5-FU) pharmacology. TMEM97 knockdown was reported to inhibit 5-fluorouracil resistance by regulating epithelial-mesenchymal transition and ABC transporter expression via inactivating the Akt/mTOR pathway in 5-fluorouracil-resistant colorectal cancer cells. This suggests that transporter and efflux systems can modulate drug sensitivity, and that uracil transport pathways may influence treatment outcomes.
Solid tumour metabolism and solute carrier targeting
Solute carrier transporters are increasingly recognized as therapeutic targets in solid tumours. Inhibitors of monocarboxylate transporter 1 and 4 have been reviewed as potential therapeutics for treating solid tumours, with structure-activity relationship insights. Although these transporters are not uracil transporters themselves, they illustrate the pharmacological tractability of solute carrier proteins and provide context for targeting uracil transport in cancer metabolism.
Enamel maturation and ion transport
STIM1 and SLC24A4 have been reported to be critical for enamel maturation. While this study focuses on calcium and ion transport rather than uracil, it demonstrates how solute carrier and transport-related proteins contribute to tissue development and mineralization, providing a broader physiological context for transporter biology.
Herbicide discovery targeting uracil-related pathways
Novel cyclopropyl-uracil derivatives have been designed and synthesized as potent herbicides, with activity and structure-activity relationship studies reported. This work highlights the agricultural and pharmacological relevance of uracil-based compounds and their interactions with cellular targets, reinforcing the importance of understanding uracil transport and metabolism.
From uracil transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for uracil transport? | CRISPR knockout of the candidate transporter gene followed by uracil flux assay |
| Does a specific residue determine substrate specificity? | Point mutation at the predicted binding site, guided by UraA structure |
| Can a transporter be redirected to a new substrate? | Point mutation such as UapA F569S to broaden specificity |
| Does uracil transport affect drug resistance? | Knockout or knockdown of transporter genes in 5-FU-resistant cancer cells |
| Can transporter expression be monitored in live cells? | Tagged knock-in of a fluorescent or epitope tag |
| Does overexpression of a transporter increase uracil uptake? | Overexpression of the candidate transporter in a heterologous system |
How to Study the uracil transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uracil flux assay | Rate and extent of uracil transport | Functional validation of candidate transporters |
| Crystal structure / cryo-EM | Three-dimensional structure of transporter | Mechanistic understanding of UraA and related proteins |
| Site-directed mutagenesis | Effect of specific residues on transport | Mapping substrate-binding and specificity determinants |
| CRISPR knockout | Requirement of a gene for transport | Loss-of-function studies in cell models |
| Knockdown (siRNA/shRNA) | Reduction of transporter expression | Phenotypic studies in cancer cells |
| Western blot / qPCR | Protein and mRNA expression levels | Correlating transporter expression with function |
| Pathway inhibitor treatment | Signaling dependence of transport phenotype | Testing Akt/mTOR involvement in resistance |
| Heterologous expression | Transport activity in a controlled system | Characterizing human transporters such as hENT1 |
Transport assays with radiolabeled uracil
Radiolabeled uracil flux assays are a direct way to measure uracil transmembrane transporter activity. Such assays can be performed in cells expressing candidate transporters, including hENT1, to determine whether uracil is transported and to quantify kinetics. These experiments provide functional evidence that complements structural and genetic data.
Structural biology and homology modeling
Crystal structures of UraA have provided the structural basis for uracil transport and the elevator-type alternating-access mechanism. Homology modeling based on these structures can be used to predict substrate-binding residues in related transporters and to design point-mutation experiments. Structural data also help interpret the relationship between uracil transporters and the SLC4/23/26 superfamily.
Genetic and CRISPR-based perturbation
CRISPR knockout and point-mutation models allow researchers to test the causal role of specific transporters and residues. For example, the UapA F569S substitution demonstrates how a single point mutation can alter substrate specificity. In cancer models, knockdown of TMEM97 has been used to probe 5-fluorouracil resistance mechanisms. These approaches can be combined with transport assays to link genotype to function.
Expression and pathway analysis
Gene expression and pathway analyses can reveal how uracil transporters are regulated in disease contexts. Studies of 5-FU-resistant colorectal cancer cells have examined EMT markers, ABC transporters, and Akt/mTOR signaling after TMEM97 knockdown. Such analyses help place uracil transmembrane transporter activity within broader cellular networks and identify candidate therapeutic targets.
How CRISPR Can Be Used to Study GO:0015210 uracil transmembrane transporter activity
Knockout
CRISPR knockout of a candidate uracil transporter gene can determine whether the gene is required for uracil transmembrane transport. Loss-of-function models are particularly useful when combined with radiolabeled flux assays or growth assays in pyrimidine-limited conditions. Knockout studies of transporter-related genes such as TMEM97 have also been used to probe drug resistance phenotypes.
Point Mutation
Point mutations can be introduced to test the role of specific residues in substrate binding and specificity. The UapA F569S substitution is a classic example of a single point mutation that converts a specific transporter into a broad-specificity transporter. Similar strategies can be guided by the UraA structure to dissect uracil recognition.
Knock-in
Knock-in of a tagged or reporter version of a transporter gene allows expression and localization to be monitored in a native context. This approach can complement structural studies of UraA and related transporters by linking protein localization to transport activity. Tagged knock-in models are also useful for validating antibody specificity and for imaging studies.
Overexpression
Overexpression of a candidate transporter in a heterologous system can provide direct evidence of transport activity. For example, hENT1 has been expressed and characterized to demonstrate nucleobase transport, including uracil. Overexpression models are valuable for kinetic studies and for testing inhibitors or substrates.
How EDITGENE Supports uracil transmembrane transporter activity Research
Researchers studying uracil transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in uracil transport, drug resistance, or pyrimidine metabolism. Establishing causality requires well-controlled genetic models that can isolate the contribution of a single transporter or residue from the broader cellular context. EDITGENE provides CRISPR-based tools and services designed to support these experiments, from knockout to precise point mutation and knock-in.
Contact EDITGENE today to design your custom CRISPR model for uracil transmembrane transporter activity research.
Frequently Asked Questions About uracil transmembrane transporter activity
What is uracil transmembrane transporter activity?
Uracil transmembrane transporter activity (GO:0015210) is a molecular function that enables the transfer of uracil, 2,4-dioxopyrimidine, from one side of a membrane to the other.
What is the GO ID for uracil transmembrane transporter activity?
The Gene Ontology ID is GO:0015210, and the official name is uracil transmembrane transporter activity.
What genes are involved in uracil transmembrane transporter activity?
Genes and proteins include the bacterial uracil:proton symporter uraA, human SLC29A1 (hENT1), and the fungal transporter UapA, among others.
What is the synonym for GO:0015210?
The synonym is uracil/uridine permease activity.
How does UraA transport uracil?
UraA is a uracil:proton symporter that uses an elevator-type alternating-access mechanism, as revealed by crystal structures.
Can hENT1 transport uracil?
Yes, human equilibrative nucleoside transporter 1 (hENT1/SLC29A1) has been shown to transport uracil and other nucleobases.
Why is uracil transport important in cancer?
Uracil transport intersects with 5-fluorouracil pharmacology; TMEM97 knockdown inhibited 5-FU resistance by regulating EMT and ABC transporters via the Akt/mTOR pathway in colorectal cancer cells.
How can I study uracil transmembrane transporter activity in the lab?
Common approaches include radiolabeled uracil flux assays, structural biology, site-directed mutagenesis, and CRISPR knockout or knockdown models.
What is the relationship between uracil transporters and the SLC4/23/26 superfamily?
The dimeric structure of UraA provided mechanistic insights into the SLC4/23/26 transporter superfamily, linking uracil transport to a broader group of solute carriers.
Are there drugs that target uracil-related transport?
Cyclopropyl-uracil derivatives have been developed as herbicides, and inhibitors of monocarboxylate transporters 1 and 4 are being explored for solid tumours, illustrating pharmacological interest in solute carrier transporters.
Conclusion
GO:0015210, uracil transmembrane transporter activity, defines a specific molecular function that is central to pyrimidine salvage, RNA metabolism, and drug response. Structural studies of UraA have provided a mechanistic framework for understanding how uracil crosses membranes, while human transporters such as hENT1 demonstrate the diversity of proteins that can carry out this activity. The link between uracil transport and 5-fluorouracil resistance highlights its translational relevance in cancer. Researchers can investigate this activity using transport assays, structural biology, and CRISPR-based genetic models. By combining knockout, point-mutation, knock-in, and overexpression approaches, it is possible to establish causal relationships between specific genes or residues and uracil transport phenotypes, ultimately informing both basic biology and therapeutic development.
References
- 1. Pei H et al.. 2026. Novel Cyclopropyl-Uracil Derivatives as Potent Herbicides: Design, Synthesis, Activity, and Structure-Activity Relationship.. J Agric Food Chem 74(29):22771-22783 PMID: 42470364
- 2. Lu F et al.. 2011. Structure and mechanism of the uracil transporter UraA.. Nature 472(7342):243-6 PMID: 21423164
- 3. Puri S et al.. 2020. Monocarboxylate transporter 1 and 4 inhibitors as potential therapeutics for treating solid tumours: A review with structure-activity relationship insights.. Eur J Med Chem 199:112393 PMID: 32388280
- 4. Yao SY et al.. 2011. Nucleobase transport by human equilibrative nucleoside transporter 1 (hENT1).. J Biol Chem 286(37):32552-62 PMID: 21795683
- 5. Yu X et al.. 2017. Dimeric structure of the uracil:proton symporter UraA provides mechanistic insights into the SLC4/23/26 transporters.. Cell Res 27(8):1020-1033 PMID: 28621327
- 6. Wang S et al.. 2014. STIM1 and SLC24A4 Are Critical for Enamel Maturation.. J Dent Res 93(7 Suppl):94S-100S PMID: 24621671
- 7. Xu Y et al.. 2024. TMEM97 knockdown inhibits 5-fluorouracil resistance by regulating epithelial-mesenchymal transition and ABC transporter expression via inactivating the Akt/mTOR pathway in 5-fluorouracil-resistant colorectal cancer cells.. Chem Biol Drug Des 103(2):e14490 PMID: 38388887
- 8. Amillis S et al.. 2001. Substitution F569S converts UapA, a specific uric acid-xanthine transporter, into a broad specificity transporter for purine-related solutes.. J Mol Biol 313(4):765-74 PMID: 11697902
