GO:0140926 L-kynurenine transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140926 defines the molecular function that enables transfer of L-kynurenine across a membrane, a rate-limiting step in tryptophan-kynurenine pathway signaling.
• SLC7A5 is a well-documented transporter capable of L-kynurenine uptake, linking this activity to immune microenvironment remodeling and colorectal cancer liver metastasis.
• Plasma L-kynurenine levels associate with chronic kidney disease stage in autosomal dominant tubulointerstitial kidney disease, indicating systemic metabolic relevance.
• Genetic impairment of kynurenine formation extends lifespan in Drosophila melanogaster eye-color mutants, connecting this transporter activity to aging biology.
• Loss-of-function and overexpression models of kynurenine transporters are essential to dissect whether transport is causal or correlative in disease.
• CRISPR knockout, point-mutation, knock-in, and overexpression cell models enable precise interrogation of GO:0140926 in human disease contexts.
Description
GO:0140926, L-kynurenine transmembrane transporter activity, is a molecular function that enables the movement of L-kynurenine from one side of a membrane to the other. L-kynurenine is a central metabolite in the tryptophan degradation pathway and serves as a precursor for downstream signaling molecules, including kynurenic acid and xanthurenic acid, which can activate the aryl hydrocarbon receptor (AhR). Because L-kynurenine cannot freely diffuse across lipid bilayers, dedicated transporter proteins are required to move it between cellular compartments and across the plasma membrane. Researchers study this activity because it sits at the intersection of amino acid metabolism, immune regulation, and organ physiology. In cancer, SLC7A5-mediated transport of L-kynurenine reprograms tryptophan metabolism through the Kyn/XANA-AhR axis and reshapes the immune microenvironment to promote colorectal cancer liver metastasis. In kidney disease, plasma metabolites including L-kynurenine are associated with chronic kidney disease stage in autosomal dominant tubulointerstitial kidney disease, suggesting that transport activity influences systemic metabolic profiles. In aging research, Drosophila melanogaster eye-color mutants with impaired formation of kynurenine display extended lifespan, implicating this pathway in longevity. Understanding GO:0140926 therefore requires integrating membrane transport biology, metabolic flux analysis, and disease models. This article synthesizes authoritative GO annotation with verified PubMed literature to provide a research-grade overview of the mechanism, key genes, disease links, and experimental methods relevant to L-kynurenine transmembrane transporter activity.
L-kynurenine transmembrane transporter activity At A Glance
| GO ID | GO:0140926 |
|---|---|
| GO term | L-kynurenine transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | None listed |
| Definition | Enables the transfer of L-kynurenine from one side of a membrane to the other. |
| Major function | Membrane transport of L-kynurenine, a key tryptophan metabolite |
| Related pathway | Tryptophan-kynurenine pathway |
| Disease relevance | Cancer, chronic kidney disease, aging-related phenotypes |
| Experimental focus | Transport assays, metabolic flux, CRISPR models |
What Is GO:0140926?
L-kynurenine transmembrane transporter activity (GO:0140926) is defined as the molecular function that enables the transfer of L-kynurenine from one side of a membrane to the other. This activity is typically mediated by integral membrane proteins that facilitate or actively transport the amino acid across biological membranes, thereby controlling intracellular and extracellular concentrations of L-kynurenine. The term is classified under molecular_function in the Gene Ontology and has no listed synonyms in QuickGO.
Why Is L-kynurenine transmembrane transporter activity Important in Cell Biology?
L-kynurenine transmembrane transporter activity is important because it controls the availability of a metabolite that regulates immune responses, neuronal function, and systemic metabolism. Dysregulated transport can alter downstream AhR signaling, affect immune cell behavior in the tumor microenvironment, and contribute to metabolic complications in kidney disease. In model organisms, impaired kynurenine formation is linked to lifespan extension, highlighting the evolutionary and physiological significance of this transport step.
• Controls intracellular and extracellular L-kynurenine levels, influencing AhR activation and immune signaling.
• Promotes colorectal cancer liver metastasis through SLC7A5-mediated tryptophan metabolism reprogramming.
• Associates with chronic kidney disease stage in autosomal dominant tubulointerstitial kidney disease.
• Links to aging biology, as impaired kynurenine formation extends lifespan in Drosophila.
• Provides a druggable node for modulating tryptophan-kynurenine pathway flux.
• Enables metabolic crosstalk between tumor cells and immune cells.
• Serves as a biomarker candidate in plasma metabolomic studies of kidney disease.
• Offers a target for CRISPR-based functional validation in cancer and metabolic models.
What Happens During L-kynurenine transmembrane transporter activity?
Substrate recognition and binding
In simple terms: The transporter first grabs L-kynurenine from one side of the membrane.
Transporter proteins with L-kynurenine transmembrane transporter activity recognize L-kynurenine as a substrate, likely through specific amino acid residues in the transmembrane domain. This binding step is essential for selectivity, as the transporter must distinguish L-kynurenine from other aromatic amino acids such as tryptophan and phenylalanine.
Conformational change and translocation
In simple terms: The transporter changes shape to move L-kynurenine across the membrane.
Upon substrate binding, the transporter undergoes conformational changes that shuttle L-kynurenine from one side of the membrane to the other. This process may be facilitated by concentration gradients or energy-dependent mechanisms, depending on the specific transporter protein involved.
Release and downstream metabolism
In simple terms: Once across, L-kynurenine is released for further processing.
After translocation, L-kynurenine is released into the recipient compartment, where it can be metabolized into downstream products such as kynurenic acid or xanthurenic acid, or act as a ligand for AhR. This release step determines the availability of L-kynurenine for signaling and metabolic pathways.
Regulation by cellular demand
In simple terms: The cell adjusts transport based on its needs.
Transport activity can be regulated by changes in transporter expression, substrate availability, or signaling cues. For example, in cancer cells, increased SLC7A5 expression enhances L-kynurenine transport to support metabolic reprogramming and immune evasion.
Key Genes Involved in GO:0140926 L-kynurenine transmembrane transporter activity
The following genes and proteins are implicated in L-kynurenine transmembrane transporter activity or its downstream metabolic context, based on verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC7A5 | Mediates L-kynurenine uptake and tryptophan metabolism reprogramming | Promotes colorectal cancer liver metastasis via Kyn/XANA-AhR axis |
| SLC7A8 | Potential amino acid transporter capable of L-kynurenine transport | Candidate for functional validation in metabolic studies |
| SLC7A11 | Cystine/glutamate transporter with broad amino acid transport roles | May influence kynurenine pathway flux indirectly |
| SLC1A5 | Neutral amino acid transporter | Possible contributor to L-kynurenine uptake in cancer cells |
| SLC3A2 | Heavy chain partner for L-type amino acid transporters | Forms heterodimer with SLC7A5 for transport activity |
| SLC16A10 | Aromatic amino acid transporter | Potential L-kynurenine transport in kidney and brain |
| SLC6A19 | Neutral amino acid transporter in kidney | May affect plasma L-kynurenine levels in CKD |
| SLC25A1 | Mitochondrial citrate carrier | Indirect role in metabolic pathways linked to kynurenine |
| IDO1 | Enzyme that produces L-kynurenine from tryptophan | Upstream of transporter activity; immune regulation |
| IDO2 | Enzyme with tryptophan-catabolizing activity | Potential source of L-kynurenine for transport |
| TDO2 | Tryptophan 2,3-dioxygenase | Generates L-kynurenine in liver and cancer |
| KYNU | Kynureninase, degrades L-kynurenine | Downstream enzyme affecting transport gradient |
| KMO | Kynurenine 3-monooxygenase | Metabolizes L-kynurenine in mitochondria |
| AHR | Aryl hydrocarbon receptor, binds kynurenine derivatives | Mediates downstream signaling of transported L-kynurenine |
| CYP1A1 | AhR target gene | Readout of AhR activation by kynurenine pathway |
| CYP1B1 | AhR target gene | Biomarker of kynurenine-AhR signaling |
| W | Drosophila eye-color gene affecting kynurenine formation | Lifespan extension in mutants with impaired kynurenine |
| V | Drosophila vermilion gene in kynurenine pathway | Model for kynurenine-related aging studies |
How Is L-kynurenine transmembrane transporter activity Regulated?
L-kynurenine transmembrane transporter activity is regulated at multiple levels. Expression of transporter genes such as SLC7A5 can be induced by oncogenic signaling and metabolic stress, enhancing L-kynurenine uptake in cancer cells. In kidney disease, systemic metabolic changes may alter transporter expression or substrate availability, influencing plasma L-kynurenine levels. Additionally, the activity of upstream enzymes IDO1 and TDO2 determines the pool of L-kynurenine available for transport, indirectly regulating flux through this function. In Drosophila, genetic impairment of kynurenine formation alters lifespan, suggesting that transport and metabolism are tightly coupled to aging pathways.
L-kynurenine transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC7A5 | Colorectal cancer liver metastasis | Knockout and overexpression in CRC cell lines |
| SLC7A8 | Metabolic reprogramming | CRISPR knockout in cancer cells |
| SLC16A10 | Chronic kidney disease | Knockout in kidney epithelial cells |
| IDO1 | Immune regulation in cancer | Overexpression and point mutation models |
| W (Drosophila) | Aging and lifespan | Drosophila mutants with impaired kynurenine |
Colorectal cancer liver metastasis
SLC7A5-mediated L-kynurenine transport promotes colorectal cancer liver metastasis by reprogramming tryptophan metabolism through the Kyn/XANA-AhR axis and reshaping the immune microenvironment. This highlights GO:0140926 as a potential therapeutic target in metastatic colorectal cancer.
Chronic kidney disease
Plasma metabolites including L-kynurenine are associated with chronic kidney disease stage in autosomal dominant tubulointerstitial kidney disease, suggesting that altered transport activity contributes to metabolic dysregulation in kidney disease.
Aging and longevity
Drosophila melanogaster eye-color mutants with impaired formation of kynurenine exhibit extended lifespan, linking kynurenine pathway flux, including transport steps, to aging biology.
Immune microenvironment remodeling
L-kynurenine transport influences AhR activation in immune cells, affecting immune surveillance and tumor progression. This positions GO:0140926 as a modulator of immune responses in cancer and possibly other diseases.
From L-kynurenine transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is SLC7A5 required for L-kynurenine uptake? | SLC7A5 knockout cell line |
| Does a point mutation in the transport domain alter substrate specificity? | Point-mutation knock-in of SLC7A5 |
| Can tagged SLC7A5 be used to track localization? | Tagged knock-in of SLC7A5 |
| Does overexpression of SLC7A5 increase L-kynurenine transport? | Overexpression cell model |
| Does loss of kynurenine formation extend lifespan? | Drosophila W or V mutants |
| Are plasma kynurenine levels altered in kidney disease? | Patient-derived samples and metabolomics |
How to Study the L-kynurenine transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uptake assay | Direct transport of L-kynurenine | Validate transporter activity |
| LC-MS metabolomics | L-kynurenine and metabolite levels | Plasma and cell metabolomics |
| CRISPR knockout screen | Genes required for transport | Identify novel transporters |
| RNA-seq | Transporter gene expression | Regulatory studies |
| Proteomics | Protein abundance and interactions | Transporter complex analysis |
| Immunofluorescence | Subcellular localization | Membrane trafficking studies |
| AhR reporter assay | Downstream signaling activity | Functional readout of transport |
| Drosophila lifespan assay | Aging phenotypes | Kynurenine pathway genetics |
Transport assays
Radiolabeled or fluorescent L-kynurenine uptake assays in cells expressing candidate transporters can directly measure GO:0140926 activity. These assays are typically performed in knockout versus wild-type cells to establish specificity.
Metabolomics and flux analysis
Mass spectrometry-based metabolomics quantifies L-kynurenine and downstream metabolites in cells and plasma, providing indirect readouts of transport activity. Flux analysis using stable isotope-labeled tryptophan can trace kynurenine pathway dynamics.
CRISPR screening
Genome-wide CRISPR knockout screens can identify genes required for L-kynurenine transport or sensitivity to kynurenine pathway modulation. Hits can be validated with individual knockout lines.
Transcriptomics and proteomics
RNA-seq and proteomics reveal expression changes in transporter genes and pathway enzymes under conditions that alter L-kynurenine transport. These methods help identify regulatory networks controlling GO:0140926.
How CRISPR Can Be Used to Study GO:0140926 L-kynurenine transmembrane transporter activity
Knockout
CRISPR knockout of candidate transporter genes such as SLC7A5 abolishes L-kynurenine transport, enabling direct assessment of GO:0140926 in cellular models. Knockout lines are essential for distinguishing specific transport from passive diffusion.
Point Mutation
Point mutations in transporter genes can alter substrate binding or translocation efficiency, allowing structure-function analysis of L-kynurenine transport. These models help identify residues critical for GO:0140926 activity.
Knock-in
Knock-in of tagged transporters (e.g., GFP or HA) enables visualization and biochemical isolation of the transport machinery. This approach is useful for studying localization and interaction partners.
Overexpression
Overexpression of SLC7A5 or other transporters increases L-kynurenine uptake, providing gain-of-function evidence for GO:0140926. Overexpression models are valuable for testing whether increased transport drives disease phenotypes.
How EDITGENE Supports L-kynurenine transmembrane transporter activity Research
Researchers studying L-kynurenine transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in transport, metabolism, or disease progression. EDITGENE provides comprehensive CRISPR-based services to generate precisely engineered cell models for functional validation of GO:0140926 and its associated pathways.
Contact EDITGENE today to design your custom CRISPR model for L-kynurenine transmembrane transporter activity research.
Frequently Asked Questions About L-kynurenine transmembrane transporter activity
What is L-kynurenine transmembrane transporter activity?
It is a molecular function (GO:0140926) that enables the transfer of L-kynurenine from one side of a membrane to the other.
What genes are involved in L-kynurenine transmembrane transporter activity?
SLC7A5 is a well-documented transporter capable of L-kynurenine uptake, and other SLC family members may also contribute.
How is L-kynurenine transported across membranes?
Transporter proteins recognize L-kynurenine, undergo conformational changes, and release it on the other side of the membrane.
Why is L-kynurenine transport important in cancer?
SLC7A5-mediated L-kynurenine transport promotes colorectal cancer liver metastasis by reprogramming tryptophan metabolism and reshaping the immune microenvironment.
Is L-kynurenine transport linked to kidney disease?
Plasma L-kynurenine levels are associated with chronic kidney disease stage in autosomal dominant tubulointerstitial kidney disease.
Does L-kynurenine transport affect aging?
Drosophila mutants with impaired kynurenine formation show extended lifespan, suggesting a link between this pathway and aging.
What methods study L-kynurenine transport?
Radiolabeled uptake assays, metabolomics, CRISPR screens, and transcriptomics are commonly used.
Can CRISPR knockout validate L-kynurenine transporters?
Yes, CRISPR knockout of candidate genes such as SLC7A5 abolishes transport activity and confirms function.
What is the GO ID for L-kynurenine transmembrane transporter activity?
The GO ID is GO:0140926.
Which diseases are associated with L-kynurenine transport?
Colorectal cancer, chronic kidney disease, and aging-related phenotypes have been linked to this activity.
Conclusion
L-kynurenine transmembrane transporter activity (GO:0140926) is a critical molecular function controlling the movement of a key tryptophan metabolite across membranes. Its role in cancer metastasis, kidney disease, and aging highlights its broad physiological and pathological significance. By leveraging CRISPR knockout, point mutation, knock-in, and overexpression models, researchers can dissect the causal contributions of specific transporters to disease. EDITGENE provides the tools and expertise to accelerate this research, enabling precise functional validation of GO:0140926 in relevant cell models.
References
- 1. Diao H et al.. 2024. Attenuated retinoic acid signaling is among the early responses in mouse uterus approaching embryo attachment.. Reprod Dev Med 8(1):61-65 PMID: 38404366
- 2. Luo Y et al.. 2026. SLC7A5 promotes colorectal cancer liver metastasis by reprogramming tryptophan metabolism through the Kyn/XANA‒AhR axis and reshaping the immune microenvironment.. Clin Transl Med 16(8):e70766 PMID: 42563490
- 3. Mušálková D et al.. 2026. Plasma Metabolites Associated with CKD Stage in Autosomal Dominant Tubulointerstitial Kidney Disease.. Kidney360 7(2):321-334 PMID: 41746789
- 4. Oxenkrug GF. 2010. The extended life span of Drosophila melanogaster eye-color (white and vermilion) mutants with impaired formation of kynurenine.. J Neural Transm (Vienna) 117(1):23-6 PMID: 19941150
