GO:0089718 amino acid import across plasma membrane: Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0089718 describes the directed movement of an amino acid from outside a cell, across the plasma membrane, and into the cytosol.
• Plasma membrane amino acid import is mediated by solute carrier (SLC) transporters that couple amino acid uptake to ion gradients or exchange.
• These transporters control nutrient supply for protein synthesis, energy metabolism, and neurotransmitter precursor availability.
• Dysregulated amino acid import is linked to cancer progression, metabolic disease, and neurological disorders.
• Key experimental approaches include CRISPR knockout, transport assays, metabolomics, and tracer flux analysis.
• EDITGENE provides knockout, point-mutation, knock-in, overexpression cell models and CRISPR library screening to study amino acid transporters.
Description
Amino acid import across plasma membrane (GO:0089718) is the biological process by which amino acids are moved from the extracellular space across the plasma membrane into the cytosol. This process is essential for providing cells with the building blocks for protein synthesis and for supplying precursors for metabolic pathways, including creatine and carnitine synthesis. The directed movement of amino acids is mediated by specific transporter proteins that reside in the plasma membrane and use electrochemical gradients or exchange mechanisms to drive uptake. Researchers study this process to understand how cells acquire nutrients, how transporter mutations contribute to disease, and how transport can be targeted therapeutically. For example, the creatine transporter SLC6A8 mediates creatine import, and its inhibition suppresses colon cancer progression. Similarly, L-type amino acid transporters transport thyroid hormones, linking amino acid import to endocrine signaling. Because amino acid import is fundamental to cell physiology, its dysregulation is implicated in cancer, metabolic disorders, and neurological conditions.
amino acid import across plasma membrane At A Glance
| GO ID | GO:0089718 |
|---|---|
| GO term | amino acid import across plasma membrane |
| Ontology | biological_process |
| Synonym | amino acid import into cell, amino acid transmembrane import, L-amino acid import, L-amino acid uptake |
| Major function | Transport of amino acids from the extracellular space into the cytosol |
| Cellular location | Plasma membrane |
| Representative transporters | SLC6A8, SLC7A5, SLC7A11, SLC1A5, SLC38A2 |
| Associated diseases | Cancer, metabolic disorders, neurological disorders |
| Research methods | CRISPR knockout, transport assays, metabolomics, tracer flux analysis |
What Is GO:0089718?
GO:0089718, amino acid import across plasma membrane, is defined as the directed movement of an amino acid from outside of a cell, across the plasma membrane, and into the cytosol. This process includes the transmembrane import of L-amino acids and is synonymous with amino acid import into cell, amino acid transmembrane import, L-amino acid import, and L-amino acid uptake. It is a biological process that requires transporter proteins to facilitate the passage of amino acids through the lipid bilayer, often against their concentration gradient by coupling to ion gradients.
Why Is amino acid import across plasma membrane Important in Cell Biology?
Amino acid import across the plasma membrane is a fundamental process that controls the intracellular availability of amino acids for protein synthesis, energy production, and biosynthesis of specialized metabolites. It is critical for normal physiology, as evidenced by the role of the creatine transporter SLC6A8 in maintaining creatine levels, which are essential for energy homeostasis in tissues such as muscle and brain. Dysregulation of amino acid transporters is associated with cancer, where tumor cells increase amino acid uptake to support rapid proliferation. Moreover, amino acid transporters can mediate the uptake of hormones and drugs, influencing endocrine and pharmacological responses. Understanding this process at the molecular level is therefore essential for developing targeted therapies and for interpreting metabolic phenotypes in disease models.
• Provides essential amino acids for protein synthesis and cell growth.
• Supplies precursors for specialized metabolites such as creatine and carnitine.
• Regulates nutrient signaling pathways, including mTORC1.
• Mediates the uptake of thyroid hormones via L-type amino acid transporters.
• Is a therapeutic target in cancer, as shown for SLC6A8 in colon cancer.
• Contributes to metabolic reprogramming in proliferating cells.
• Influences neurotransmitter precursor availability in the brain.
• Can be studied using CRISPR-based genetic models to dissect transporter function.
• Relevant to drug delivery, as transporters can mediate drug uptake.
• Dysregulation is linked to metabolic and neurological disorders.
What Happens During amino acid import across plasma membrane?
Substrate recognition and binding
In simple terms: The transporter protein recognizes and grabs the amino acid outside the cell.
Amino acid import begins when a plasma membrane transporter binds its specific amino acid substrate from the extracellular environment. Transporters exhibit selectivity for particular amino acids or classes of amino acids, such as L-type amino acids, which is determined by the structure of the substrate-binding site. For example, the creatine transporter SLC6A8 specifically recognizes creatine, a derivative of amino acids, and its binding is essential for uptake. Molecular modelling studies of L-type amino acid transporters have provided insights into how thyroid hormones are recognized as substrates, highlighting the structural basis of substrate specificity.
Translocation across the lipid bilayer
In simple terms: The transporter changes shape to move the amino acid through the cell membrane.
After binding, the transporter undergoes conformational changes that translocate the amino acid across the plasma membrane into the cytosol. This process often requires energy, which is provided by coupling to the movement of ions such as sodium or by exchanging one amino acid for another. The direction of transport is determined by the electrochemical gradients maintained by ion pumps. For instance, SLC6A8-mediated creatine import is driven by sodium and chloride gradients, and its activity can be modulated by inhibitors.
Release into the cytosol
In simple terms: Once inside, the amino acid is released so the cell can use it.
Following translocation, the amino acid is released into the cytosol, where it becomes available for metabolic pathways, protein synthesis, or further transport into organelles. The release step is crucial for maintaining a concentration gradient that favors continued import. In the case of creatine, once inside the cell, it is phosphorylated to phosphocreatine, which serves as an energy buffer. Similarly, imported amino acids can be used for mitochondrial carnitine synthesis, as shown for SLC25A45-mediated import of methylated amino acids into mitochondria, although this is a distinct mitochondrial process.
Coupling to cellular metabolism
In simple terms: Imported amino acids feed into the cell's metabolic needs.
Imported amino acids are rapidly utilized in biosynthetic and energy-producing pathways. For example, creatine imported via SLC6A8 supports ATP regeneration in tissues with high energy demand. Amino acids such as methionine and its derivatives can be imported into mitochondria for carnitine synthesis, linking plasma membrane import to mitochondrial metabolism. This coupling ensures that amino acid supply matches cellular demand and is critical for maintaining metabolic homeostasis.
Key Genes Involved in GO:0089718 amino acid import across plasma membrane
The following genes encode transporters and related proteins that mediate or regulate amino acid import across the plasma membrane, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC6A8 | Creatine transporter; mediates creatine import | Target in colon cancer; modulates human creatine levels |
| SLC7A5 | L-type amino acid transporter; transports large neutral amino acids and thyroid hormones | Thyroid hormone transport; cancer metabolism |
| SLC7A11 | Cystine/glutamate antiporter; imports cystine for glutathione synthesis | Redox balance; cancer therapy resistance |
| SLC1A5 | Neutral amino acid transporter; imports glutamine and other amino acids | Cancer metabolism; mTORC1 activation |
| SLC38A2 | Sodium-coupled neutral amino acid transporter; imports small neutral amino acids | Nutrient signaling; cell growth |
| SLC3A2 | Heavy subunit of L-type amino acid transporters; chaperone for SLC7A5 | Stabilizes transporter complex; cancer |
| SLC25A45 | Mitochondrial transporter for methylated amino acids | Carnitine synthesis; mitochondrial import |
| SLC6A19 | Neutral amino acid transporter; imports neutral amino acids in kidney and intestine | Hartnup disorder; renal amino acid transport |
| SLC36A1 | Proton-coupled amino acid transporter; imports small amino acids | mTORC1 signaling; lysosomal amino acid sensing |
| SLC43A1 | L-type amino acid transporter; imports branched-chain amino acids | Cancer metabolism; insulin signaling |
| SLC43A2 | L-type amino acid transporter; imports methionine and branched-chain amino acids | Cancer; immune cell function |
| SLC16A10 | Aromatic amino acid transporter; imports thyroid hormones and aromatic amino acids | Thyroid hormone transport |
| SLC5A8 | Sodium-coupled monocarboxylate transporter; transports short-chain fatty acids and amino acid derivatives | Tumor suppressor; metabolic regulation |
| SLC12A2 | Sodium-potassium-chloride cotransporter; indirectly affects amino acid transport | Cell volume regulation; neurological disorders |
| SLC9A3 | Sodium-hydrogen exchanger; regulates intracellular pH and amino acid transport | Renal and intestinal transport |
| SLC15A1 | Peptide transporter; imports di- and tripeptides, including amino acid derivatives | Drug delivery; intestinal absorption |
| SLC7A1 | Cationic amino acid transporter; imports arginine and lysine | Nitric oxide synthesis; immune function |
| SLC7A2 | Cationic amino acid transporter; imports arginine and lysine | Macrophage function; cancer |
How Is amino acid import across plasma membrane Regulated?
Amino acid import across the plasma membrane is regulated at multiple levels to match cellular demand. The mechanistic target of rapamycin complex 1 (mTORC1) senses intracellular amino acid levels and promotes transporter expression and activity, creating a feedback loop that supports cell growth. For example, SLC6A8-mediated creatine import can influence mTORC1 signaling, and its inhibition suppresses colon cancer progression. Additionally, transporter activity can be regulated by post-translational modifications, such as phosphorylation, and by changes in membrane trafficking. Hormonal signals, including thyroid hormones, can also affect the expression of L-type amino acid transporters, linking endocrine status to amino acid uptake. In the kidney, amino acid transporters are regulated to maintain systemic amino acid homeostasis, and their dysfunction leads to disorders such as Hartnup disease.
amino acid import across plasma membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC6A8 | Creatine transporter deficiency; colon cancer | Knockout and overexpression cell models; transport assays |
| SLC7A5 | Cancer; thyroid hormone transport | Point mutation and knockout models; tracer uptake |
| SLC6A19 | Hartnup disorder | Knockout models; amino acid transport assays |
| SLC25A45 | Carnitine synthesis; mitochondrial import | Knockout and knock-in models; metabolomics |
| SLC7A11 | Cancer; oxidative stress | Knockout and overexpression models; glutathione assays |
Cancer metabolism and amino acid import
Many cancer cells upregulate amino acid transporters to support rapid proliferation and survival. SLC6A8, the creatine transporter, is overexpressed in colon cancer, and its therapeutic targeting suppresses tumor progression and modulates human creatine levels. L-type amino acid transporters such as SLC7A5 are also overexpressed in various cancers and contribute to the uptake of essential amino acids and thyroid hormones, which can promote tumor growth. Targeting these transporters is a promising strategy for cancer therapy.
Neurological and metabolic disorders
Defects in amino acid import can lead to neurological and metabolic disorders. For instance, mutations in SLC6A19 cause Hartnup disorder, characterized by impaired neutral amino acid transport in the kidney and intestine. Creatine transporter deficiency, caused by mutations in SLC6A8, leads to intellectual disability and seizures due to impaired creatine uptake in the brain. These examples highlight the importance of amino acid import for normal brain function and systemic metabolism.
Thyroid hormone transport and endocrine disorders
L-type amino acid transporters, such as SLC7A5 and SLC16A10, mediate the cellular uptake of thyroid hormones, which are critical for development and metabolism. Dysregulation of these transporters can affect thyroid hormone availability and contribute to endocrine disorders. Molecular modelling studies have provided insights into how thyroid hormones bind to these transporters, offering potential targets for therapeutic intervention.
From amino acid import across plasma membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SLC6A8 affect creatine import and cancer growth? | SLC6A8 knockout cell lines |
| How do point mutations in SLC7A5 alter thyroid hormone transport? | SLC7A5 point-mutation knock-in cells |
| Can overexpression of SLC1A5 increase glutamine uptake? | SLC1A5 overexpression cell models |
| What is the role of SLC25A45 in mitochondrial carnitine synthesis? | SLC25A45 knockout and tagged knock-in cells |
| Does SLC7A11 mediate cystine import for glutathione synthesis? | SLC7A11 knockout cells |
| How does SLC6A19 dysfunction affect amino acid homeostasis? | SLC6A19 knockout organoids |
How to Study the amino acid import across plasma membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled uptake assay | Rate of amino acid import | Functional characterization of transporters |
| CRISPR knockout screen | Genes required for amino acid import | Discovery of novel transporters |
| Metabolomics | Intracellular amino acid levels and metabolites | Metabolic profiling of transport mutants |
| Stable isotope tracing | Flux of amino acids into metabolic pathways | Quantifying creatine synthesis |
| Molecular modelling | Substrate binding and transport mechanism | Predicting transporter specificity |
| Cryo-EM | Three-dimensional structure of transporters | Understanding conformational changes |
| RNA-seq | Expression of amino acid transporters | Identifying transporter isoforms in tissues |
| Proteomics | Protein abundance and interactions | Detecting transporter complexes |
Transport assays using radiolabeled amino acids
Radiolabeled amino acid uptake assays are the gold standard for measuring import activity across the plasma membrane. Cells are incubated with a radiolabeled amino acid, and the amount of intracellular radioactivity is quantified to determine transport rates. This method can be used to assess the function of specific transporters, such as SLC6A8, and to evaluate the effects of inhibitors or mutations.
CRISPR-based genetic screens
CRISPR knockout screens can identify genes required for amino acid import and cellular fitness. By transducing cells with a genome-wide sgRNA library and selecting for cells with altered amino acid uptake or survival, researchers can discover novel transporters and regulators. This approach has been used to identify SLC6A8 as a mediator of creatine import in colon cancer.
Metabolomics and tracer flux analysis
Metabolomics and stable isotope tracing allow researchers to track the fate of imported amino acids and their contribution to metabolic pathways. For example, 13C-labeled amino acids can be used to measure the incorporation of carbon into downstream metabolites such as creatine or carnitine. These methods provide a systems-level view of amino acid import and metabolism.
Molecular modelling and structural studies
Molecular modelling and structural biology techniques, such as cryo-EM, can reveal how transporters recognize and translocate amino acids. These approaches have been used to understand the mechanism of choline and ethanolamine transport and to model thyroid hormone binding to L-type amino acid transporters. Such insights are valuable for designing specific inhibitors or modulators.
How CRISPR Can Be Used to Study GO:0089718 amino acid import across plasma membrane
Knockout
CRISPR knockout of amino acid transporter genes, such as SLC6A8 or SLC7A11, is used to abolish import activity and study the consequences for cell growth, metabolism, and signaling. Knockout cell lines can be validated by transport assays and metabolomics, and they serve as powerful tools to establish causality between a transporter and a phenotype.
Point Mutation
CRISPR point mutation can introduce specific amino acid substitutions in transporter genes to dissect the molecular basis of substrate recognition, ion coupling, or regulation. For example, mutations in the substrate-binding site of SLC7A5 can reveal residues critical for thyroid hormone transport. These models are valuable for understanding transporter structure-function relationships.
Knock-in
CRISPR knock-in can be used to insert tags, such as fluorescent proteins or epitope tags, into endogenous transporter genes to study their localization, trafficking, and interactions. Tagged knock-in models allow real-time imaging of transporters in live cells and enable biochemical purification of transporter complexes.
Overexpression
CRISPR-mediated overexpression, often achieved by knocking in a strong promoter or by using CRISPR activation (CRISPRa), can increase the expression of amino acid transporters to study their gain-of-function effects. Overexpression models are useful for testing whether increased import is sufficient to drive phenotypes such as enhanced proliferation or metabolic reprogramming.
How EDITGENE Supports amino acid import across plasma membrane Research
Researchers studying amino acid import across plasma membrane-related genes often need to determine whether a candidate gene is causally involved in transport, metabolism, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models, enabling rigorous functional studies of amino acid transporters and their regulatory networks.
Contact EDITGENE today to design your custom CRISPR model for amino acid import across plasma membrane research.
Frequently Asked Questions About amino acid import across plasma membrane
What is amino acid import across plasma membrane (GO:0089718)?
GO:0089718 describes the directed movement of an amino acid from outside a cell, across the plasma membrane, and into the cytosol.
What genes are involved in amino acid import across plasma membrane?
Key genes include SLC6A8, SLC7A5, SLC7A11, SLC1A5, SLC38A2, and many other solute carrier (SLC) transporters.
How is amino acid import regulated?
It is regulated by nutrient signaling pathways such as mTORC1, by ion gradients, and by post-translational modifications of transporters.
Why is amino acid import important for cancer?
Cancer cells often upregulate amino acid transporters to support rapid growth; targeting these transporters can suppress tumor progression.
What diseases are linked to defects in amino acid import?
Mutations in transporters can cause Hartnup disorder, creatine transporter deficiency, and contribute to cancer and metabolic disorders.
What methods are used to study amino acid import?
Common methods include radiolabeled uptake assays, CRISPR screens, metabolomics, and molecular modelling.
Can CRISPR be used to study amino acid transporters?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect transporter function.
What is the role of SLC6A8 in amino acid import?
SLC6A8 is a creatine transporter that mediates creatine import; its inhibition suppresses colon cancer progression.
How do L-type amino acid transporters work?
They transport large neutral amino acids and thyroid hormones across the plasma membrane, often in exchange for other amino acids.
What is the clinical relevance of amino acid import?
It is relevant for cancer therapy, metabolic disorders, neurological diseases, and drug delivery.
Conclusion
Amino acid import across the plasma membrane (GO:0089718) is a fundamental biological process that supplies cells with essential nutrients and regulates metabolism, signaling, and growth. Dysregulation of this process is implicated in cancer, metabolic disorders, and neurological diseases, making it a compelling area of research. Advances in CRISPR-based models and analytical methods are enabling precise dissection of transporter function and the development of targeted therapies. Continued investigation of amino acid import will deepen our understanding of cellular physiology and provide new opportunities for therapeutic intervention.
References
- 1. Khan A et al.. 2025. Machine-learning-guided discovery of SLC25A45 as a mediator of mitochondrial methylated amino acid import and carnitine synthesis.. Cell Metab 37(11):2220-2232.e8 PMID: 41075780
- 2. Kurth I et al.. 2021. Therapeutic targeting of SLC6A8 creatine transporter suppresses colon cancer progression and modulates human creatine levels.. Sci Adv 7(41):eabi7511 PMID: 34613776
- 3. Ri K et al.. 2024. Molecular mechanism of choline and ethanolamine transport in humans.. Nature 630(8016):501-508 PMID: 38778100
- 6. Krause G et al.. 2017. Thyroid hormone transport across L-type amino acid transporters: What can molecular modelling tell us?. Mol Cell Endocrinol 458:68-75 PMID: 28341457
- 7. Verrey F et al.. 2005. Novel renal amino acid transporters.. Annu Rev Physiol 67:557-72 PMID: 15709970
