GO:0015804 neutral amino acid transport: Cellular Nutrient Uptake, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015804 neutral amino acid transport describes the directed movement of neutral amino acids (amino acids with no net charge) into, out of, or within a cell via transporters or pores.
• The process is mediated by multiple solute carrier (SLC) families, including SLC6A19, SLC6A15, SLC6A20, and the heteromeric amino acid transporter complex LAT1-4F2hc.
• Neutral amino acid transport is essential for nutrient uptake, metabolic reprogramming, and cell survival, particularly in T cell activation and perinatal neuronal development.
• Dysregulation of neutral amino acid transport is linked to metabolic disorders, neurological diseases, and cancer, making transporters attractive therapeutic targets.
• Research methods to study this process include transport assays, structural biology, CRISPR knockout models, and metabolic flux analysis.
• EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression, and library screening services to dissect neutral amino acid transport mechanisms.
Description
Neutral amino acid transport (GO:0015804) is a fundamental biological process that governs the movement of amino acids with no net charge across cellular membranes. This process is critical for maintaining intracellular amino acid pools, supporting protein synthesis, and fueling metabolic pathways. Transporters responsible for this process are integral membrane proteins that facilitate the uptake of essential amino acids, which cannot be synthesized de novo. The regulation of neutral amino acid transport is tightly linked to cellular signaling, immune function, and neuronal activity. In recent years, the importance of neutral amino acid transport has been highlighted in diverse physiological and pathological contexts. For instance, the inhibition of SLC6A19, a major neutral amino acid transporter in the kidney, promotes urinary amino acid excretion and lowers plasma phenylalanine, offering a potential therapy for phenylketonuria. In the brain, large neutral amino acid levels tune perinatal neuronal excitability and survival, underscoring the role of these transporters in neurodevelopment. Furthermore, antigen receptor signaling controls amino acid transport to coordinate metabolic reprogramming essential for T cell differentiation, linking this process to immune responses. Given its broad impact, understanding the molecular mechanisms, regulation, and disease associations of neutral amino acid transport is vital for researchers in cell biology, neuroscience, immunology, and pharmacology. This article provides a comprehensive overview of GO:0015804, covering its definition, key genes, regulatory mechanisms, disease relevance, and cutting-edge research methods, including CRISPR-based approaches.
neutral amino acid transport At A Glance
| GO ID | GO:0015804 |
|---|---|
| GO term | neutral amino acid transport |
| Ontology | biological_process |
| Synonym | none |
| Major function | Mediates the movement of neutral amino acids across cellular membranes, supporting nutrient uptake, metabolism, and signaling. |
| Key transporters | SLC6A19, SLC6A15, SLC6A20, LAT1 (SLC7A5), 4F2hc (SLC3A2), and other SLC family members. |
| Cellular locations | Plasma membrane, apical and basolateral membranes of epithelial cells, synaptic membranes. |
| Associated diseases | Phenylketonuria, Hartnup disorder, neurological disorders, cancer, immune deficiencies. |
| Research methods | Transport assays, structural biology, CRISPR screens, metabolomics, electrophysiology. |
What Is GO:0015804?
GO:0015804 neutral amino acid transport is defined as the directed movement of neutral amino acids, which are amino acids with no net charge, into, out of, or within a cell, or between cells, by means of some agent such as a transporter or pore. This process encompasses the translocation of neutral amino acids across biological membranes, typically mediated by specific integral membrane proteins that recognize and shuttle these solutes. Neutral amino acids include glycine, alanine, serine, cysteine, threonine, valine, leucine, isoleucine, methionine, phenylalanine, tyrosine, tryptophan, proline, and others. The transport can be facilitated by uniporters, symporters, or antiporters, and is often coupled to ion gradients or other driving forces.
Why Is neutral amino acid transport Important in Cell Biology?
Neutral amino acid transport is essential for cellular homeostasis, as it supplies cells with amino acids required for protein synthesis, energy production, and biosynthesis of neurotransmitters and nucleotides. It plays a pivotal role in immune cell activation, where antigen receptor signaling triggers metabolic reprogramming that depends on amino acid uptake. In the nervous system, neutral amino acid transporters regulate neurotransmitter precursors and neuronal excitability, influencing brain development and function. Dysregulation of these transporters is implicated in a range of diseases, including metabolic disorders like phenylketonuria, neurological conditions, and cancer, making them promising therapeutic targets.
• Supplies essential neutral amino acids for protein synthesis and cell growth.
• Regulates metabolic reprogramming in activated T cells and immune responses.
• Controls neuronal excitability and survival during perinatal development.
• Involved in kidney amino acid reabsorption and homeostasis.
• Target for treating phenylketonuria via SLC6A19 inhibition.
• Associated with Hartnup disorder and other transportopathies.
• Modulates drug pharmacokinetics by affecting amino acid drug transport.
• Plays a role in cancer metabolism and tumor growth.
• Provides structural insights for drug design targeting transporters.
• Impacts livestock nutrition and intestinal absorption.
What Happens During neutral amino acid transport?
Substrate recognition and binding
In simple terms: The transporter first recognizes and grabs the specific neutral amino acid it will carry.
Neutral amino acid transporters exhibit substrate specificity determined by the shape and chemical properties of the amino acid side chain. For example, the SLC6A19 transporter recognizes a broad range of neutral amino acids, including phenylalanine, methionine, and leucine, through a binding pocket that accommodates hydrophobic and polar side chains. Structural studies of the amino acid transporter complex have revealed that substrate binding induces conformational changes in the transporter, which are essential for subsequent translocation. The binding affinity and selectivity are critical for proper physiological function, as mutations in the binding site can lead to transport defects and disease.
Conformational change and translocation
In simple terms: After binding, the transporter changes shape to move the amino acid across the membrane.
Following substrate binding, the transporter undergoes a series of conformational changes that expose the bound amino acid to the opposite side of the membrane. This alternating access mechanism involves the opening and closing of intracellular and extracellular gates. Recent structural insights into the substrate transport mechanism of the amino acid transporter complex have elucidated how the heteromeric LAT1-4F2hc complex coordinates substrate translocation. The process is often driven by ion gradients, such as sodium or chloride, which provide the energy for concentrative transport.
Release of amino acid into the cytoplasm
In simple terms: The amino acid is released inside the cell, ready for use.
Once the transporter adopts an inward-facing conformation, the neutral amino acid is released into the cytoplasm. This step is crucial for maintaining intracellular amino acid pools. For instance, in kidney epithelial cells, the release of neutral amino acids across the basolateral membrane is mediated by different transporters, ensuring vectorial transport from the tubular lumen to the blood. In T cells, the release of amino acids such as leucine into the cytoplasm activates mTORC1 signaling, which drives metabolic reprogramming and differentiation.
Regulation by signaling pathways
In simple terms: The transport process is turned up or down by cellular signals.
Neutral amino acid transport is dynamically regulated by various signaling pathways. Antigen receptor signaling in T cells controls the expression and activity of amino acid transporters, coordinating metabolic reprogramming essential for T cell differentiation. In the brain, large neutral amino acid levels tune perinatal neuronal excitability and survival, indicating that transport activity is modulated during development. Additionally, the SLC6A19 transporter is regulated by hormones and dietary factors, affecting plasma amino acid levels. These regulatory mechanisms ensure that amino acid supply matches cellular demand.
Physiological integration and homeostasis
In simple terms: The body balances amino acid levels through transport in different organs.
Neutral amino acid transport is integrated across tissues to maintain systemic amino acid homeostasis. In the kidney, transporters in the proximal tubule reabsorb filtered amino acids, preventing their loss in urine. In the intestine, transporters mediate the absorption of dietary amino acids, as studied in pigs with special consideration of L-methionine. The coordination of transport across the blood-brain barrier, liver, muscle, and other tissues ensures proper amino acid distribution for protein synthesis and metabolism. Disruption of this integration leads to metabolic disorders and disease.
Key Genes Involved in GO:0015804 neutral amino acid transport
The following genes encode transporters and associated proteins that mediate or regulate neutral amino acid transport (GO:0015804).
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC6A19 | Major neutral amino acid transporter in kidney and intestine; mediates reabsorption of neutral amino acids. | Target for phenylketonuria; knockout reduces plasma phenylalanine. |
| SLC6A15 | Neuronal neutral amino acid transporter; regulates synaptic amino acid levels. | Implicated in neuropsychiatric disorders; studied for neuronal excitability. |
| SLC6A20 | Neutral amino acid transporter in kidney and intestine; transports proline and other amino acids. | Associated with iminoglycinuria; potential drug target. |
| SLC7A5 (LAT1) | Light chain of the LAT1-4F2hc complex; transports large neutral amino acids. | Overexpressed in cancer; target for tumor imaging and therapy. |
| SLC3A2 (4F2hc) | Heavy chain of heteromeric amino acid transporters; essential for LAT1 function. | Required for T cell activation and metabolic reprogramming. |
| SLC1A5 | Neutral amino acid transporter for glutamine and other amino acids. | Supports cancer cell metabolism; studied in T cells. |
| SLC38A1 | System A transporter; mediates sodium-dependent neutral amino acid transport. | Regulated by antigen receptor signaling in T cells. |
| SLC38A2 | System A transporter; transports small neutral amino acids. | Involved in mTORC1 activation and cell growth. |
| SLC7A8 (LAT2) | Light chain of LAT2-4F2hc; transports small neutral amino acids. | Expressed in kidney and intestine; role in amino acid reabsorption. |
| SLC16A10 (TAT1) | Aromatic amino acid transporter; transports phenylalanine, tyrosine, tryptophan. | Linked to phenylketonuria and thyroid hormone transport. |
| SLC43A1 (LAT3) | System L transporter; mediates sodium-independent neutral amino acid transport. | Potential target in cancer and metabolic diseases. |
| SLC43A2 (LAT4) | System L transporter; transports large neutral amino acids. | Studied in placental and brain amino acid transport. |
| SLC6A18 | Neutral amino acid transporter in kidney; transports glycine and other amino acids. | Associated with iminoglycinuria and kidney function. |
| SLC6A19 | Apical neutral amino acid transporter in intestine and kidney. | Hartnup disorder gene; knockout models available. |
| SLC3A1 | Heavy chain of heteromeric transporters; partners with SLC7A9. | Mutations cause cystinuria; related to neutral amino acid transport. |
| SLC7A9 | Light chain of heteromeric transporter; transports cystine and neutral amino acids. | Cystinuria gene; studied in kidney transport. |
How Is neutral amino acid transport Regulated?
Neutral amino acid transport is regulated at multiple levels, including transcriptional, post-transcriptional, and post-translational mechanisms. Antigen receptor signaling in T cells induces the expression of amino acid transporters such as SLC7A5 and SLC38A1, which is essential for metabolic reprogramming and differentiation. The mTORC1 pathway senses intracellular amino acid levels and regulates transporter expression and activity, creating a feedback loop that matches transport capacity to cellular demand. In the kidney, hormones such as insulin and glucagon modulate the activity of neutral amino acid transporters, affecting amino acid reabsorption. Additionally, substrate availability and ion gradients influence transport rates, and mutations in transporter genes can alter regulation, leading to disease.
neutral amino acid transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC6A19 | Phenylketonuria; Hartnup disorder | Knockout mouse, point mutation knock-in, transport assays. |
| SLC6A15 | Neuropsychiatric disorders; neuronal excitability | Conditional knockout, electrophysiology, behavioral tests. |
| SLC7A5 (LAT1) | Cancer; immune cell metabolism | Overexpression, knockout in cancer cell lines, xenograft models. |
| SLC3A2 (4F2hc) | Immune disorders; T cell differentiation | Knockout in T cells, metabolic flux analysis. |
| SLC7A9 | Cystinuria | Knockout mouse, kidney transport studies. |
Phenylketonuria and metabolic disorders
Phenylketonuria (PKU) is an inherited metabolic disorder characterized by elevated plasma phenylalanine due to deficiency of phenylalanine hydroxylase. Inhibition of the neutral amino acid transporter SLC6A19 has been shown to facilitate urinary neutral amino acid excretion and lower plasma phenylalanine, offering a novel therapeutic strategy for PKU. This highlights the critical role of neutral amino acid transport in maintaining amino acid homeostasis and its potential as a drug target for metabolic diseases.
Neurological and neurodevelopmental disorders
Neutral amino acid transporters in the brain regulate the availability of neurotransmitter precursors and influence neuronal excitability. Large neutral amino acid levels tune perinatal neuronal excitability and survival, and disruptions in this process can lead to neurodevelopmental disorders. The SLC6A15 transporter has been implicated in neuropsychiatric conditions, and its dysfunction may contribute to altered synaptic amino acid levels and neuronal activity. Understanding these mechanisms is crucial for developing therapies for neurological diseases.
Cancer and immune disorders
Cancer cells often upregulate neutral amino acid transporters to support rapid growth and metabolism. For example, LAT1 (SLC7A5) is overexpressed in many tumors and is associated with poor prognosis. In immune cells, antigen receptor signaling controls amino acid transport to coordinate metabolic reprogramming essential for T cell differentiation; dysregulation can lead to immune disorders. Targeting these transporters is a promising approach for cancer therapy and immune modulation.
Kidney transportopathies
In the kidney, neutral amino acid transporters are essential for reabsorbing filtered amino acids. Mutations in SLC6A19 cause Hartnup disorder, characterized by neutral aminoaciduria and a range of symptoms including photosensitive rash and neurological issues. Other transporters such as SLC7A9 and SLC3A1 are involved in cystinuria, a disorder of amino acid transport in the kidney. These transportopathies underscore the importance of neutral amino acid transport in renal physiology.
From neutral amino acid transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does SLC6A19 inhibition lower plasma phenylalanine? | SLC6A19 knockout mouse, point mutation knock-in. |
| How do neutral amino acids affect neuronal excitability? | Conditional knockout of SLC6A15 in neurons, electrophysiology. |
| What is the role of amino acid transport in T cell differentiation? | CRISPR knockout of SLC7A5 or SLC3A2 in primary T cells. |
| What is the structural basis of substrate transport? | Cryo-EM of LAT1-4F2hc complex, mutagenesis. |
| How is intestinal neutral amino acid transport regulated? | Intestinal epithelial cell lines, knockout of SLC6A19. |
| Can overexpression of LAT1 drive cancer growth? | LAT1 overexpression in cancer cell lines, xenograft models. |
How to Study the neutral amino acid transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uptake assay | Transport rate and substrate specificity | Characterization of SLC6A19 and other transporters. |
| Cryo-EM | Three-dimensional structure of transporter complexes | Understanding substrate translocation mechanism. |
| CRISPR knockout screen | Genes required for transport and cell survival | Identifying novel regulators of amino acid transport. |
| Metabolomics | Intracellular and extracellular amino acid concentrations | Metabolic reprogramming in T cells and cancer. |
| Electrophysiology | Ion currents associated with transport | Neuronal excitability and transporter function. |
| RNA-seq | Transcriptional changes in transporter genes | Regulation by antigen receptor signaling. |
| Proteomics | Protein expression and interactions | Identifying transporter complexes. |
| Intestinal perfusion | Amino acid absorption in vivo | Studying neutral amino acid transport in pigs. |
Transport assays
Radiolabeled or fluorescent amino acid uptake assays are used to measure the rate and specificity of neutral amino acid transport in cells or membrane vesicles. These assays can be performed in cell lines overexpressing specific transporters or in primary cells, and are often coupled with inhibitors to dissect transporter contributions.
Structural biology
Cryo-electron microscopy and X-ray crystallography provide high-resolution structures of neutral amino acid transporters, revealing substrate binding sites and conformational changes. Structural insights into the substrate transport mechanism of the amino acid transporter complex have advanced our understanding of how these proteins function.
CRISPR-based genetic screens
Genome-wide CRISPR knockout screens can identify genes essential for neutral amino acid transport and cellular fitness under different amino acid conditions. These screens are powerful for discovering novel transporters and regulatory pathways.
Metabolomics and flux analysis
Mass spectrometry-based metabolomics quantifies intracellular and extracellular amino acid levels, while flux analysis traces the fate of transported amino acids. These methods are used to study metabolic reprogramming in immune cells and cancer cells.
How CRISPR Can Be Used to Study GO:0015804 neutral amino acid transport
Knockout
CRISPR knockout of neutral amino acid transporter genes, such as SLC6A19 or SLC7A5, allows researchers to study loss-of-function phenotypes, including changes in amino acid uptake, metabolic profiles, and cell growth. For example, SLC6A19 knockout mice exhibit increased urinary neutral amino acid excretion and lower plasma phenylalanine. Knockout models are essential for validating the role of specific transporters in physiological and disease contexts.
Point Mutation
CRISPR point mutation can introduce disease-associated missense mutations into transporter genes to model transportopathies and study structure-function relationships. For instance, mutations in SLC6A19 that cause Hartnup disorder can be recapitulated in cell lines or animal models to assess transport activity and substrate specificity. Point mutations in the substrate binding site can reveal critical residues for amino acid recognition.
Knock-in
CRISPR knock-in can be used to insert tags (e.g., GFP, HA) or reporter genes into endogenous transporter loci, enabling real-time visualization and quantification of transporter expression and localization. Knock-in of fluorescent tags into SLC7A5 or SLC3A2 allows tracking of transporter dynamics in live cells. Additionally, knock-in of human disease mutations into mouse orthologs creates accurate models for studying pathogenesis.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression can drive high-level expression of neutral amino acid transporters to study their function in gain-of-function settings. Overexpression of LAT1 (SLC7A5) in cancer cell lines promotes growth and metabolic reprogramming, mimicking the upregulation observed in tumors. Overexpression models are useful for drug screening and identifying downstream signaling pathways.
How EDITGENE Supports neutral amino acid transport Research
Researchers studying neutral amino acid transport-related genes often need to determine whether a candidate gene is causally involved in amino acid uptake, metabolic regulation, or disease pathogenesis. EDITGENE provides a comprehensive suite of CRISPR-based services to accelerate this discovery process, from gene knockout to precise point mutations and knock-in models.
Contact EDITGENE today to design your custom CRISPR model for neutral amino acid transport research.
Frequently Asked Questions About neutral amino acid transport
What is neutral amino acid transport GO:0015804?
GO:0015804 neutral amino acid transport is the biological process of moving neutral amino acids (amino acids with no net charge) across cell membranes via transporters or pores.
What genes are involved in neutral amino acid transport?
Key genes include SLC6A19, SLC6A15, SLC6A20, SLC7A5 (LAT1), SLC3A2 (4F2hc), SLC1A5, SLC38A1, SLC38A2, and others.
Why is neutral amino acid transport important for cells?
It supplies essential amino acids for protein synthesis, energy production, and signaling, and regulates metabolic reprogramming in immune cells and neurons.
How is neutral amino acid transport regulated?
It is regulated by signaling pathways such as antigen receptor signaling and mTORC1, as well as by substrate availability and hormones.
What diseases are associated with defects in neutral amino acid transport?
Diseases include phenylketonuria, Hartnup disorder, cystinuria, neurological disorders, and cancer.
What methods are used to study neutral amino acid transport?
Methods include radiolabeled uptake assays, cryo-EM, CRISPR screens, metabolomics, and electrophysiology.
Can CRISPR be used to study neutral amino acid transport?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are powerful tools to dissect transporter function and disease mechanisms.
What is the role of SLC6A19 in neutral amino acid transport?
SLC6A19 is a major apical transporter in kidney and intestine that mediates reabsorption of neutral amino acids; its inhibition lowers plasma phenylalanine.
How does LAT1 (SLC7A5) contribute to neutral amino acid transport?
LAT1 forms a heteromeric complex with 4F2hc to transport large neutral amino acids and is often overexpressed in cancer.
What are the therapeutic implications of targeting neutral amino acid transporters?
Targeting transporters like SLC6A19 or LAT1 offers potential therapies for metabolic disorders, cancer, and immune diseases.
Conclusion
Neutral amino acid transport (GO:0015804) is a vital biological process that underpins cellular metabolism, immune function, and neuronal activity. The diverse family of transporters involved, including SLC6A19, LAT1, and others, highlights the complexity and importance of this process in health and disease. Dysregulation of neutral amino acid transport is linked to a spectrum of disorders, from phenylketonuria to cancer, making these transporters attractive therapeutic targets. Advances in structural biology, CRISPR-based genetic models, and metabolomics are accelerating our understanding of the molecular mechanisms and regulatory networks controlling neutral amino acid transport. EDITGENE's comprehensive CRISPR services empower researchers to dissect these pathways with precision, from knockout to knock-in and overexpression models, facilitating the development of novel diagnostics and therapeutics.
References
- 1. Wobst HJ et al.. 2024. SLC6A19 inhibition facilitates urinary neutral amino acid excretion and lowers plasma phenylalanine.. JCI Insight 9(21) PMID: 39513367
- 2. Knaus LS et al.. 2023. Large neutral amino acid levels tune perinatal neuronal excitability and survival.. Cell 186(9):1950-1967.e25 PMID: 36996814
- 3. Sinclair LV et al.. 2013. Control of amino-acid transport by antigen receptors coordinates the metabolic reprogramming essential for T cell differentiation.. Nat Immunol 14(5):500-8 PMID: 23525088
- 4. Kukułowicz J et al.. 2023. The SLC6A15-SLC6A20 Neutral Amino Acid Transporter Subfamily: Functions, Diseases, and Their Therapeutic Relevance.. Pharmacol Rev 76(1):142-193 PMID: 37940347
- 5. Verrey F et al.. 2009. Kidney amino acid transport.. Pflugers Arch 458(1):53-60 PMID: 19184091
- 6. Yang H et al.. 2025. Structural insights into the substrate transport mechanism of the amino acid transporter complex.. J Biol Chem 301(9):110569 PMID: 40780412
- 7. Schermuly II et al.. 2024. Transport of Neutral Amino Acids in the Jejunum of Pigs with Special Consideration of L-Methionine.. Nutrients 16(19) PMID: 39408384
