GO:0015187 glycine transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015187 (glycine transmembrane transporter activity) is a molecular function that enables the transfer of glycine across a membrane.
• Glycine transporters are members of the SLC6 family, which can oligomerize and are regulated by interacting proteins.
• Glycinergic transmission depends on vesicular packaging and reuptake of glycine by transporters such as GLYT2 (SLC6A5).
• The SLC6A18 transporter is proposed to function as a Na-dependent glycine/urea antiporter in the kidney, influencing urea secretion and glomerular filtration rate.
• Mutations in glycine transporter genes can cause hyperekplexia, and chloride channelopathies affecting glycine receptors lead to neurological disorders.
• Studying glycine transport requires methods such as patch-clamp, radiolabeled uptake, and CRISPR-based models to dissect gene function.
Description
Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem, and its concentration in the synaptic cleft is tightly controlled by specific transporters. The Gene Ontology term GO:0015187, glycine transmembrane transporter activity, describes the molecular function responsible for moving glycine across cellular membranes. This activity is essential for terminating glycinergic signaling and for supplying glycine for metabolic processes. Dysregulation of glycine transport has been linked to neurological disorders such as hyperekplexia and to kidney dysfunction. Understanding the molecular players and regulatory mechanisms of glycine transport is therefore critical for both basic neurobiology and clinical research.
glycine transmembrane transporter activity At A Glance
| GO ID | GO:0015187 |
|---|---|
| GO term | glycine transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | glycine betaine/proline porter activity; glycine transporter activity; proline/glycine/betaine:hydrogen/sodium symporter activity |
| Major function | Transfer of glycine across a membrane |
| Major protein families | SLC6 family (e.g., SLC6A5, SLC6A9, SLC6A18) |
| Cellular location | Plasma membrane, synaptic vesicles |
| Associated processes | Glycinergic neurotransmission, amino acid homeostasis, urea secretion |
| Disease relevance | Hyperekplexia, chloride channelopathies, kidney disorders |
What Is GO:0015187?
Glycine transmembrane transporter activity (GO:0015187) is a molecular function that enables the transfer of glycine, the simplest amino acid, from one side of a membrane to the other. This activity is typically mediated by integral membrane proteins that couple glycine movement to the electrochemical gradient of ions such as sodium or chloride. The term encompasses transporters that may also accept related substrates like proline or betaine, as reflected in synonyms such as glycine betaine/proline porter activity.
Why Is glycine transmembrane transporter activity Important in Cell Biology?
Glycine transmembrane transporter activity is fundamental for controlling extracellular glycine levels, which directly impacts inhibitory neurotransmission and excitatory NMDA receptor signaling. Impaired glycine transport can lead to excessive excitation, as seen in hyperekplexia, or contribute to kidney dysfunction through altered urea handling. Moreover, glycine transporters are potential drug targets for neurological and psychiatric conditions. Thus, understanding this activity at the molecular level is essential for developing therapeutic interventions.
• Regulates inhibitory glycinergic neurotransmission in the spinal cord and brainstem.
• Modulates NMDA receptor co-agonism by controlling glycine availability at excitatory synapses.
• Mutations in glycine transporter genes cause hyperekplexia, a neurological disorder.
• SLC6A18 dysfunction is linked to altered urea secretion and glomerular filtration rate.
• Glycine transporters are targets for analgesics and treatments of psychiatric disorders.
• Chloride channelopathies affecting glycine receptors highlight the importance of transport in neuronal inhibition.
• Glycine transport is essential for metabolic pathways such as glutathione synthesis and one-carbon metabolism.
• Oligomerization of SLC6 transporters affects their trafficking and function.
• Glycine transporters can transport related amino acids like proline and betaine, influencing osmolyte balance.
• Studying glycine transport aids in understanding synaptic plasticity and network excitability.
Mechanism, Genes and Research Methods
Substrate Recognition and Binding
In simple terms: The transporter first grabs glycine from one side of the membrane.
Glycine transporters, such as those in the SLC6 family, recognize glycine through specific binding pockets formed by transmembrane helices. The binding site accommodates the amino acid's amino and carboxyl groups, and in some transporters, related substrates like proline or betaine can also bind. This initial recognition step is crucial for selectivity and is coupled to ion binding, typically sodium and chloride.
Conformational Changes and Translocation
In simple terms: The transporter changes shape to move glycine across the membrane.
Upon substrate binding, the transporter undergoes conformational changes that alternately expose the binding site to either side of the membrane, a mechanism known as the alternating access model. This process is driven by the electrochemical gradient of sodium ions. For vesicular transporters, a proton gradient may drive glycine uptake into synaptic vesicles. The cycle completes when glycine is released on the other side, and the transporter resets.
Oligomerization and Interacting Proteins
In simple terms: Transporters often work in groups and with partner proteins.
SLC6 transporters can form oligomers, which may influence their trafficking, stability, and transport activity. They also interact with proteins like syntaxin 1A and syntenin, which regulate their surface expression and function. These interactions are important for fine-tuning glycinergic signaling.
Regulation by Ions and Gradients
In simple terms: The transporter relies on ion gradients to power glycine movement.
Glycine transport is typically coupled to the sodium gradient, and in some cases to chloride or proton gradients. Changes in ion concentrations can reverse transport direction, as seen in some pathological conditions. The stoichiometry of ion coupling determines the transport efficiency and directionality.
Physiological Roles in Neurotransmission and Metabolism
In simple terms: Glycine transport controls brain signaling and kidney function.
In the nervous system, glycine transporters clear glycine from synapses to terminate inhibitory signals and to supply glycine for NMDA receptor co-activation. In the kidney, SLC6A18 is proposed to act as a Na-dependent glycine/urea antiporter, affecting urea secretion and glomerular filtration rate. These diverse roles highlight the importance of glycine transport in multiple organ systems.
Key Genes Involved in GO:0015187 glycine transmembrane transporter activity
The following genes encode proteins that mediate or regulate glycine transmembrane transporter activity, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC6A5 | Neuronal glycine transporter (GLYT2) | Mutations cause hyperekplexia; target for analgesics |
| SLC6A9 | Glycine transporter 1 (GLYT1) | Regulates NMDA receptor co-agonism; implicated in psychiatric disorders |
| SLC6A18 | Kidney glycine/urea antiporter | Influences urea secretion and glomerular filtration rate |
| SLC6A7 | Proline transporter | Can transport glycine betaine; involved in osmolyte balance |
| SLC6A12 | Betaine/GABA transporter | Transports glycine betaine; role in osmoprotection |
| SLC6A1 | GABA transporter | Can transport glycine with low affinity; related to epilepsy |
| SLC6A11 | GABA transporter | May transport glycine; involved in inhibitory signaling |
| SLC6A13 | GABA transporter | Potential glycine transport; linked to neurological disorders |
| SLC6A6 | Taurine transporter | Can transport glycine; role in osmolyte regulation |
| SLC6A14 | Amino acid transporter | Transports glycine and other amino acids; cancer relevance |
| SLC6A19 | Neutral amino acid transporter | Transports glycine; mutations cause Hartnup disorder |
| SLC6A20 | Proline/glycine transporter | Transports glycine and proline; kidney and gut function |
| SLC36A1 | Proton-coupled amino acid transporter | Transports glycine; lysosomal and intestinal roles |
| SLC38A1 | System A transporter | Transports glycine; involved in glutamine and glycine homeostasis |
| SLC38A2 | System A transporter | Transports glycine; neuronal and metabolic roles |
| SLC38A5 | System N transporter | Transports glycine; regulation of neurotransmitter levels |
| SLC7A10 | Asc-1 transporter | Transports glycine; synaptic regulation |
| SLC7A11 | Cystine/glutamate antiporter | Indirectly affects glycine metabolism; cancer and oxidative stress |
How Is glycine transmembrane transporter activity Regulated?
Glycine transmembrane transporter activity is regulated at multiple levels. SLC6 transporters can oligomerize, and their surface expression is controlled by interacting proteins such as syntaxin 1A and syntenin. Phosphorylation and other post-translational modifications also modulate transporter trafficking and activity. In the kidney, SLC6A18 activity is influenced by sodium gradients and potentially by hormones affecting urea secretion. Additionally, NMDA receptor activity can feedback on glycine transporter function to maintain synaptic glycine levels.
glycine transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC6A5 | Hyperekplexia | Knockout mouse, point mutation knock-in |
| SLC6A9 | Schizophrenia, NMDA receptor hypofunction | Conditional knockout, overexpression |
| SLC6A18 | Kidney dysfunction, altered urea secretion | Knockout rat, tagged knock-in |
| SLC6A14 | Cancer (e.g., colon, breast) | Xenograft with knockout or overexpression |
| SLC7A11 | Cancer, oxidative stress | CRISPR knockout in cancer cell lines |
Hyperekplexia and Neurological Disorders
Hyperekplexia is a neurological disorder characterized by exaggerated startle responses, often caused by mutations in glycine transporter genes such as SLC6A5. Impaired glycine reuptake leads to excessive glycinergic signaling or altered NMDA receptor function, contributing to motor dysfunction. Chloride channelopathies affecting glycine receptors also disrupt inhibitory neurotransmission, highlighting the importance of transport in neuronal inhibition.
Kidney Dysfunction and Urea Handling
The SLC6A18 transporter is proposed to function as a Na-dependent glycine/urea antiporter in the proximal straight tubule, influencing urea secretion and glomerular filtration rate. Dysregulation of this transporter may contribute to kidney disorders associated with altered urea excretion.
Cancer and Metabolic Reprogramming
Glycine transport is linked to cancer metabolism, as transporters like SLC6A14 and SLC7A11 support the uptake of glycine and other amino acids required for tumor growth. Targeting glycine transport may therefore be a potential therapeutic strategy in oncology.
From glycine transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SLC6A5 affect glycinergic transmission? | SLC6A5 knockout mouse |
| How does SLC6A9 point mutation alter NMDA receptor co-agonism? | SLC6A9 point mutation knock-in mouse |
| What is the role of SLC6A18 in urea secretion? | SLC6A18 knockout rat |
| Can overexpression of SLC6A14 promote tumor growth? | SLC6A14 overexpression in cancer cell lines |
| How does tagged SLC6A5 localize in neurons? | Tagged knock-in mouse (e.g., GFP) |
| Does SLC7A11 knockout sensitize cancer cells to oxidative stress? | CRISPR knockout in cancer cell lines |
How to Study the glycine transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Patch-clamp | Transport currents | Electrogenic transport kinetics |
| Radiolabeled uptake | Glycine transport rate | Inhibitor screening |
| Fluorescence microscopy | Subcellular localization | Trafficking studies |
| CRISPR knockout | Gene function loss | Phenotypic analysis in vivo |
| Site-directed mutagenesis | Residue-specific function | Structure-function studies |
| Proteomics | Protein interactions | Identifying transporter complexes |
| RNA-seq | Gene expression changes | Transcriptional regulation |
Electrophysiology and Patch-Clamp
Patch-clamp recordings can measure glycine transporter currents in neurons or heterologous cells, revealing transport kinetics and ion coupling. This method is essential for studying the electrogenic nature of some glycine transporters.
Radiolabeled Uptake Assays
Radiolabeled glycine uptake assays in cell lines or synaptosomes quantify transport activity and allow screening for inhibitors. These assays are useful for characterizing transporter mutants and for drug discovery.
Fluorescence Imaging and Super-Resolution Microscopy
Fluorescently tagged transporters can be visualized in live cells to study trafficking, oligomerization, and surface expression. Super-resolution microscopy reveals nanoscale clustering at synapses.
CRISPR-Cas9 Genome Editing
CRISPR-Cas9 knockout or knock-in models enable the study of specific glycine transporter genes in vivo and in vitro. These models help dissect the contribution of individual transporters to physiology and disease.
How CRISPR Can Be Used to Study GO:0015187 glycine transmembrane transporter activity
Knockout
CRISPR-Cas9 knockout of glycine transporter genes such as SLC6A5 or SLC6A9 in cell lines or animal models can reveal their roles in glycinergic signaling and behavior. Knockout mice for SLC6A5 exhibit hyperekplexia-like phenotypes, validating the gene's importance.
Point Mutation
Introducing disease-associated point mutations (e.g., in SLC6A5 or SLC6A9) via CRISPR can model hyperekplexia or schizophrenia-related dysfunction. These models help understand how specific residues affect transport activity and protein interactions.
Knock-in
Knock-in of tagged versions of transporters (e.g., GFP-SLC6A5) allows real-time visualization of protein localization and dynamics in vivo. This approach is valuable for studying trafficking and synaptic targeting.
Overexpression
Overexpression of glycine transporters like SLC6A14 in cancer cell lines can promote tumor growth and alter metabolic pathways. Such models are used to test the therapeutic potential of transport inhibitors.
How EDITGENE Supports glycine transmembrane transporter activity Research
Researchers studying glycine transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in a specific physiological or pathological process. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell and animal models, enabling functional validation of glycine transporters and their regulators.
Contact EDITGENE today to design your custom CRISPR model for glycine transmembrane transporter activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC6A9 Knockout HEK293 Cell Line | EDJ-KQ2258 | Human | 6536 | Details Get a Quote |
| SLC7A8 Knockout HEK293 Cell Line | EDC08226 | Human | 23428 | Details Get a Quote |
| SLC38A5 Knockout HEK293 Cell Line | EDJ-KQ3433 | Human | 92745 | Details Get a Quote |
| SLC36A1 Knockout HEK293 Cell Line | EDJ-KQ6515 | Human | 206358 | Details Get a Quote |
| SLC32A1 Knockout HEK293 Cell Line | EDJ-KQ9792 | Human | 140679 | Details Get a Quote |
| SLC36A2 Knockout HEK293 Cell Line | EDJ-KQ11495 | Human | 153201 | Details Get a Quote |
| SLC6A20 Knockout HEK293 Cell Line | EDJ-KQ15286 | Human | 54716 | Details Get a Quote |
| SLC25A38 Knockout HEK293 Cell Line | EDJ-KQ15313 | Human | 54977 | Details Get a Quote |
| SLC36A3 Knockout HEK293 Cell Line | EDJ-KQ15336 | Human | 285641 | Details Get a Quote |
| SLC6A9 Knockout A-549 Cell Line | EDJ-KQ23950 | Human | 6536 | Details Get a Quote |
| SLC6A9 Knockout HCT 116 Cell Line | EDJ-KQ23952 | Human | 6536 | Details Get a Quote |
| SLC6A9 Knockout HeLa Cell Line | EDJ-KQ23953 | Human | 6536 | Details Get a Quote |
| SLC38A5 Knockout HCT 116 Cell Line | EDC08642 | Human | 92745 | Details Get a Quote |
| SLC38A5 Knockout HeLa Cell Line | EDJ-KQ25159 | Human | 92745 | Details Get a Quote |
| SLC6A20 Knockout HCT 116 Cell Line | EDJ-KQ45984 | Human | 54716 | Details Get a Quote |
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Frequently Asked Questions About glycine transmembrane transporter activity
What is glycine transmembrane transporter activity?
It is a molecular function (GO:0015187) that enables the transfer of glycine across a membrane, typically mediated by SLC6 family transporters.
What genes are involved in glycine transmembrane transporter activity?
Key genes include SLC6A5, SLC6A9, SLC6A18, and other SLC6 family members that transport glycine or related substrates.
How is glycine transport regulated?
It is regulated by oligomerization, interacting proteins like syntaxin 1A, ion gradients, and post-translational modifications.
What diseases are associated with glycine transporters?
Mutations in SLC6A5 cause hyperekplexia, and SLC6A18 dysfunction is linked to kidney urea handling disorders.
What is the role of glycine transporters in the brain?
They clear glycine from synapses to terminate inhibitory signaling and modulate NMDA receptor activity.
Can glycine transporters be targeted for therapy?
Yes, they are potential targets for analgesics, antipsychotics, and cancer therapeutics.
What methods are used to study glycine transport?
Patch-clamp, radiolabeled uptake, fluorescence imaging, and CRISPR-based models are commonly used.
What is the SLC6A18 transporter?
It is a kidney transporter proposed to function as a Na-dependent glycine/urea antiporter, influencing urea secretion.
How does glycine transport affect NMDA receptors?
By controlling extracellular glycine levels, transporters regulate NMDA receptor co-agonism and excitatory signaling.
What are the synonyms for GO:0015187?
Synonyms include glycine betaine/proline porter activity, glycine transporter activity, and proline/glycine/betaine:hydrogen/sodium symporter activity.
Conclusion
Glycine transmembrane transporter activity (GO:0015187) is a critical molecular function that controls glycine levels across membranes, impacting neurotransmission, metabolism, and kidney function. Dysregulation of these transporters is linked to neurological and renal diseases, making them important therapeutic targets. Continued research using advanced CRISPR models and functional assays will further elucidate their mechanisms and disease relevance.
References
- 1. Jayaraman K et al.. 2021. SLC6 transporter oligomerization.. J Neurochem 157(4):919-929 PMID: 32767560
- 2. Kirsch J. 2006. Glycinergic transmission.. Cell Tissue Res 326(2):535-40 PMID: 16807723
- 3. Planells-Cases R et al.. 2009. Chloride channelopathies.. Biochim Biophys Acta 1792(3):173-89 PMID: 19708126
- 4. Rajani V et al.. 2020. Tripartite signalling by NMDA receptors.. Mol Brain 13(1):23 PMID: 32070387
- 8. Bankir L et al.. 2024. The SLC6A18 Transporter Is Most Likely a Na-Dependent Glycine/Urea Antiporter Responsible for Urea Secretion in the Proximal Straight Tubule: Influence of This Urea Secretion on Glomerular Filtration Rate.. Nephron 148(11-12):796-822 PMID: 38824912
