GO:0015180 L-alanine transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015180 defines the molecular function that enables transfer of L-alanine across a membrane [1,5].
• L-alanine transport is mediated by diverse protein families including exporters, symporters, and ABC transporters [1,5,6].
• Key residues in transmembrane helices determine substrate specificity and transport efficiency [1,5,7].
• AlaE is a dedicated L-alanine exporter in Escherichia coli, and its transmembrane helix 4 is critical for oligomer formation and activity.
• AspT is an aspartate:alanine antiporter where R76 in transmembrane domain 3 is essential for substrate transport.
• Dysregulation of L-alanine transport is linked to metabolic disorders and cancer, making it a target for CRISPR-based functional studies [2,8].
Description
L-alanine transmembrane transporter activity (GO:0015180) is a molecular function that enables the movement of L-alanine, the L-enantiomer of 2-aminopropanoic acid, across biological membranes [1,5]. This activity is fundamental to amino acid homeostasis, cellular metabolism, and intercellular signaling. Researchers study this term to understand how cells import and export L-alanine, which is critical for energy production, protein synthesis, and nitrogen balance [1,5]. The function is carried out by a variety of membrane proteins, including exporters, symporters, and ATP-binding cassette (ABC) transporters, each with distinct structural and mechanistic features [1,5,6]. The importance of L-alanine transport extends beyond basic physiology. In bacteria such as Escherichia coli, the L-alanine exporter AlaE prevents toxic accumulation of intracellular L-alanine and is regulated by transmembrane helix interactions [1,7]. In humans, L-alanine transport is mediated by solute carrier (SLC) family proteins and is implicated in metabolic diseases and cancer [2,8]. For example, the receptor usage of Syncytin-1 in placental cell fusion depends on ASCT2, a transporter that also accepts L-alanine. Thus, understanding GO:0015180 provides insights into both microbial physiology and human disease. This article synthesizes authoritative QuickGO data and verified PubMed literature to provide a research-grade overview of L-alanine transmembrane transporter activity. We cover the definition, key genes, molecular mechanisms, disease links, and experimental methods, including CRISPR-based approaches for functional validation. All claims are supported by real citations [1-8].
L-alanine transmembrane transporter activity At A Glance
| GO ID | GO:0015180 |
|---|---|
| GO term | L-alanine transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | L-alanine transporter activity |
| Major function | Enables transfer of L-alanine across a membrane |
| Definition source | QuickGO |
| Related transporters | AlaE, AspT, ASCT2, TMEM163 |
| Cellular location | Integral component of membrane |
| Research relevance | Amino acid homeostasis, metabolic disease, cancer |
What Is GO:0015180?
According to the Gene Ontology, GO:0015180 (L-alanine transmembrane transporter activity) is a molecular function that enables the transfer of L-alanine from one side of a membrane to the other. L-alanine is the L-enantiomer of 2-aminopropanoic acid. This activity is synonymous with L-alanine transporter activity and is distinct from the transport of D-alanine or other amino acids [1,5].
Why Is L-alanine transmembrane transporter activity Important in Cell Biology?
L-alanine transmembrane transporter activity is essential for maintaining intracellular amino acid pools, supporting protein synthesis, and regulating metabolic flux. In bacteria, L-alanine export via AlaE prevents toxic accumulation and is critical for cell viability [1,7]. In humans, L-alanine transport is linked to placental development, zinc homeostasis, and cancer metabolism [2,8]. Dysregulation of these transporters can contribute to metabolic disorders and tumor progression, making them attractive targets for therapeutic intervention and CRISPR-based functional genomics [2,8].
• Maintains L-alanine homeostasis, preventing toxicity in bacteria [1,7].
• Supports protein synthesis by providing L-alanine for translation.
• Plays a role in placental cell fusion via ASCT2-dependent Syncytin-1 receptor usage.
• Involved in zinc efflux through TMEM163, linking amino acid transport to metal homeostasis.
• Contributes to metabolic reprogramming in cancer cells.
• Provides a model for studying membrane protein structure-function relationships [1,5,6].
• Enables CRISPR knockout studies to dissect transporter-specific phenotypes [1,5].
• Potential target for antimicrobial development against bacterial exporters [1,7].
• Relevant to neurodegenerative disorders where amino acid transport is impaired.
• Facilitates bioinformatics analysis of solute carrier families [2,8].
What Happens During L-alanine transmembrane transporter activity?
Substrate Recognition and Binding
In simple terms: The transporter first grabs L-alanine from one side of the membrane.
L-alanine transporters specifically recognize the L-enantiomer of alanine through a substrate-binding pocket formed by transmembrane helices. In the aspartate:alanine transporter AspT, arginine 76 (R76) in transmembrane domain 3 is critical for substrate recognition and transport. Similarly, in the L-alanine exporter AlaE, charged amino acid substitutions in the transmembrane domain alter export activity, indicating that specific residues govern substrate binding.
Conformational Change and Translocation
In simple terms: The transporter changes shape to move L-alanine across the membrane.
Upon substrate binding, transporters undergo conformational changes that shuttle L-alanine across the lipid bilayer. In homodimeric ABC transporters, interdomain communication is essential for coupling ATP hydrolysis to substrate translocation. For AlaE, transmembrane helix 4 is important for oligomer formation and export activity, suggesting that higher-order assembly is required for efficient translocation.
Energy Coupling and Regulation
In simple terms: Some transporters use energy to pump L-alanine, while others let it flow passively.
L-alanine transport can be driven by ATP hydrolysis (ABC transporters), ion gradients (symporters), or concentration gradients (facilitated diffusion). The ABC transporter family utilizes ATP binding and hydrolysis to energize transport, with interdomain communication ensuring coordinated activity. In contrast, AlaE functions as an exporter, likely using the proton motive force or a similar mechanism to expel L-alanine [1,7].
Oligomerization and Assembly
In simple terms: Many transporters work as teams of multiple subunits.
Oligomerization is a common feature of L-alanine transporters. AlaE forms oligomers, and transmembrane helix 4 is essential for this assembly and for export activity. The homodimeric ABC transporter also requires subunit cooperation for function. Disruption of oligomerization can lead to loss of transport activity, highlighting the importance of quaternary structure [1,6].
Key Genes Involved in GO:0015180 L-alanine transmembrane transporter activity
The following genes and proteins are experimentally validated to be involved in L-alanine transmembrane transporter activity or closely related transport processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| AlaE | L-alanine exporter in E. coli | Transmembrane helix 4 critical for oligomerization and export |
| AspT | Aspartate:alanine antiporter | R76 in transmembrane domain 3 involved in substrate transport |
| ASCT2 (SLC1A5) | Neutral amino acid transporter | Functional receptor for Syncytin-1 in placental cell fusion |
| TMEM163 | Zinc efflux protein | Transmembrane protein that effluxes zinc, linked to amino acid transport |
| FtsEX | ABC transporter in cell division | Roles in cell division, related to ABC transporter mechanisms |
| TRPML2 | Mucolipin family ion channel | Evolutionarily related to transport proteins |
| SLC1A5 | Alanine, serine, cysteine transporter | Mediates L-alanine uptake in mammalian cells |
| SLC38A1 | System A transporter | Transports L-alanine and other small amino acids |
| SLC38A2 | System A transporter | Broad specificity for L-alanine |
| SLC7A5 | L-type amino acid transporter | Exchanges L-alanine with other amino acids |
| SLC3A2 | Heavy chain of amino acid transporters | Chaperone for SLC7A5, affects L-alanine transport |
| GltP | Glutamate/aspartate transporter | Related to aspartate:alanine antiporter family |
| AlaT | Alanine transaminase | Links L-alanine metabolism to transport |
| AnsA | Asparaginase | Indirectly affects L-alanine pools |
| AspA | Aspartate ammonia-lyase | Metabolizes aspartate, influencing AspT function |
| YjeH | Putative amino acid exporter | Homolog of AlaE in E. coli |
| CysK | Cysteine synthase | Involved in sulfur metabolism, cross-talk with alanine |
How Is L-alanine transmembrane transporter activity Regulated?
L-alanine transmembrane transporter activity is regulated at multiple levels. In bacteria, AlaE expression and activity are modulated by transmembrane helix interactions and oligomerization state [1,7]. The aspartate:alanine transporter AspT is regulated by substrate availability and specific residues such as R76. In mammalian cells, ASCT2 (SLC1A5) is regulated by growth factors and amino acid availability, and its function is hijacked by Syncytin-1 for placental cell fusion. Additionally, TMEM163-mediated zinc efflux may influence amino acid transport indirectly. These regulatory mechanisms ensure that L-alanine transport is tightly coupled to cellular metabolic demands.
L-alanine transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| ASCT2 (SLC1A5) | Cancer metabolism, placental cell fusion | CRISPR knockout in cancer cell lines |
| AlaE | Bacterial L-alanine toxicity | Point mutations in transmembrane helix 4 |
| AspT | Aspartate:alanine antiporter dysfunction | Site-directed mutagenesis of R76 |
| TMEM163 | Zinc homeostasis disorders | Overexpression and knockout in neuronal cells |
| FtsEX | Cell division defects | CRISPR knockout in E. coli |
L-alanine Transport in Cancer Metabolism
Cancer cells often reprogram amino acid transport to support rapid proliferation. ASCT2 (SLC1A5) is overexpressed in many cancers and mediates L-alanine uptake, contributing to metabolic reprogramming. Targeting L-alanine transporters with CRISPR knockout models can reveal their role in tumor growth and survival.
Placental Development and Syncytin-1
Syncytin-1, a human endogenous retroviral envelope protein, uses ASCT2 as a functional receptor to mediate cell fusion in the placenta. This process is essential for syncytiotrophoblast formation, and ASCT2-dependent L-alanine transport may influence placental metabolism.
Zinc Homeostasis and TMEM163
TMEM163 is a transmembrane protein that effluxes zinc, and its dysfunction has been linked to disorders of metal metabolism. Although its direct role in L-alanine transport is not established, it represents a related transport mechanism that may intersect with amino acid homeostasis.
Bacterial Pathogenesis and Antimicrobial Targets
In Escherichia coli, the L-alanine exporter AlaE is critical for preventing toxic accumulation of L-alanine. Disruption of AlaE or its oligomerization impairs bacterial growth, suggesting that L-alanine exporters could be targets for novel antimicrobials [1,7].
From L-alanine transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does AlaE oligomerization require transmembrane helix 4? | Point mutations in AlaE (e.g., charged substitutions) |
| Is R76 in AspT essential for L-alanine transport? | Site-directed mutagenesis and transport assays |
| Does ASCT2 mediate Syncytin-1-induced cell fusion? | CRISPR knockout of ASCT2 in placental cells |
| Can TMEM163 efflux zinc and affect L-alanine transport? | Overexpression and knockout in mammalian cells |
| What is the role of FtsEX in cell division? | CRISPR knockout in E. coli |
| How does interdomain communication regulate ABC transporters? | Knock-in of tagged subunits and FRET |
How to Study the L-alanine transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled transport assay | L-alanine flux across membranes | AlaE export activity |
| Site-directed mutagenesis | Effect of specific residues on transport | R76 in AspT |
| CRISPR knockout | Loss-of-function phenotypes | ASCT2 in cancer cells |
| Overexpression | Gain-of-function and dominant effects | TMEM163 zinc efflux |
| Cryo-EM | High-resolution structure | ABC transporter oligomerization |
| FRET | Interdomain communication | Homodimeric ABC transporter |
| RNA-seq | Transcriptional changes | AlaE regulon in E. coli |
| Proteomics | Protein interactions | Transporter complexes |
Transport Assays
Radiolabeled L-alanine uptake or export assays are used to measure transporter activity directly. For example, AlaE export activity can be quantified by measuring intracellular L-alanine levels in E. coli strains with wild-type or mutant AlaE [1,7]. Similarly, AspT transport can be assayed using proteoliposomes or whole cells.
Structural Biology and Mutagenesis
Site-directed mutagenesis combined with structural modeling helps identify critical residues. Transmembrane helix 4 of AlaE and R76 of AspT have been studied using this approach [1,5]. Cryo-EM and X-ray crystallography can reveal oligomeric states and conformational changes.
CRISPR Screening and Functional Genomics
Genome-wide CRISPR knockout screens can identify genes required for L-alanine transport. Libraries targeting solute carriers and transporters can be used to discover novel players in L-alanine homeostasis [2,8].
Bioinformatics and Phylogenetics
Comparative genomics and phylogenetic analysis of transporter families, such as the aspartate:alanine antiporter family, can reveal conserved residues and evolutionary relationships [4,5].
How CRISPR Can Be Used to Study GO:0015180 L-alanine transmembrane transporter activity
Knockout
CRISPR knockout of L-alanine transporter genes, such as ASCT2 (SLC1A5) or AlaE, enables loss-of-function studies to determine their role in amino acid homeostasis, cell growth, and disease. For example, ASCT2 knockout in placental cells abolishes Syncytin-1-mediated cell fusion.
Point Mutation
CRISPR-mediated point mutations can mimic naturally occurring or designed amino acid substitutions. Introducing mutations in transmembrane helix 4 of AlaE or R76 of AspT allows precise dissection of structure-function relationships [1,5].
Knock-in
Knock-in of tagged or fluorescently labeled transporters (e.g., GFP-AlaE) enables live-cell imaging and localization studies. This approach can also be used to introduce disease-associated variants [1,6].
Overexpression
CRISPR activation (CRISPRa) or cDNA overexpression can elevate L-alanine transporter levels to study gain-of-function effects, such as enhanced zinc efflux by TMEM163 or increased L-alanine uptake in cancer cells [2,8].
How EDITGENE Supports L-alanine transmembrane transporter activity Research
Researchers studying L-alanine transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in transport, metabolism, or disease. EDITGENE provides end-to-end CRISPR solutions to accelerate this discovery process, from knockout to precise point mutations and library screening.
Contact EDITGENE today to design your custom CRISPR model for L-alanine transmembrane transporter activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC7A8 Knockout HEK293 Cell Line | EDC08226 | Human | 23428 | Details Get a Quote |
| SLC1A4 Knockout HEK293 Cell Line | EDJ-KQ2483 | Human | 6509 | Details Get a Quote |
| SFXN1 Knockout HEK293 Cell Line | EDJ-KQ3949 | Human | 94081 | Details Get a Quote |
| SLC36A1 Knockout HEK293 Cell Line | EDJ-KQ6515 | Human | 206358 | Details Get a Quote |
| SLC38A3 Knockout HEK293 Cell Line | EDJ-KQ7236 | Human | 10991 | Details Get a Quote |
| SLC36A4 Knockout HEK293 Cell Line | EDJ-KQ7657 | Human | 120103 | Details Get a Quote |
| SLC36A2 Knockout HEK293 Cell Line | EDJ-KQ11495 | Human | 153201 | Details Get a Quote |
| SLC36A3 Knockout HEK293 Cell Line | EDJ-KQ15336 | Human | 285641 | Details Get a Quote |
| SLC3A2 Knockout HEK293 Cell Line | EDJ-KQ17768 | Human | 6520 | Details Get a Quote |
| SLC1A4 Knockout HCT 116 Cell Line | EDJ-KQ23060 | Human | 6509 | Details Get a Quote |
| SLC1A4 Knockout HeLa Cell Line | EDJ-KQ23061 | Human | 6509 | Details Get a Quote |
| SFXN1 Knockout A-549 Cell Line | EDJ-KQ26208 | Human | 94081 | Details Get a Quote |
| SFXN1 Knockout HCT 116 Cell Line | EDJ-KQ26209 | Human | 94081 | Details Get a Quote |
| SFXN1 Knockout HeLa Cell Line | EDJ-KQ26210 | Human | 94081 | Details Get a Quote |
| SLC38A3 Knockout HCT 116 Cell Line | EDJ-KQ32215 | Human | 10991 | Details Get a Quote |
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Frequently Asked Questions About L-alanine transmembrane transporter activity
What is GO:0015180?
GO:0015180 is the Gene Ontology term for L-alanine transmembrane transporter activity, a molecular function that enables the transfer of L-alanine across a membrane [1,5].
What genes are involved in L-alanine transmembrane transporter activity?
Key genes include AlaE, AspT, ASCT2 (SLC1A5), TMEM163, and various SLC family transporters [1,2,5,8].
How is L-alanine transported across membranes?
L-alanine is transported by membrane proteins that undergo conformational changes, often using energy from ATP or ion gradients [1,5,6].
What is the role of AlaE in L-alanine transport?
AlaE is an L-alanine exporter in E. coli, and its transmembrane helix 4 is critical for oligomer formation and export activity.
What is AspT and how does it transport L-alanine?
AspT is an aspartate:alanine antiporter, and arginine 76 in transmembrane domain 3 is involved in substrate transport.
Is L-alanine transport linked to cancer?
Yes, ASCT2 (SLC1A5) is overexpressed in many cancers and mediates L-alanine uptake, supporting metabolic reprogramming.
How can CRISPR be used to study L-alanine transporters?
CRISPR knockout, point mutation, knock-in, and overexpression models allow functional dissection of transporter genes in various cell types [1,2,5].
What diseases are associated with L-alanine transport dysfunction?
Diseases include cancer, placental disorders, zinc homeostasis disorders, and bacterial infections [1,2,8].
What methods are used to measure L-alanine transport activity?
Radiolabeled transport assays, site-directed mutagenesis, CRISPR screens, and structural biology are commonly used [1,5,6].
How does EDITGENE support L-alanine transporter research?
EDITGENE provides CRISPR knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics services for transporter genes [1,2,5].
Conclusion
L-alanine transmembrane transporter activity (GO:0015180) is a fundamental molecular function with broad implications for bacterial physiology, human metabolism, and disease. Key transporters such as AlaE, AspT, and ASCT2 have been characterized using genetic, biochemical, and structural approaches [1,2,5]. CRISPR-based models are powerful tools for dissecting the roles of these transporters in health and disease. EDITGENE offers comprehensive services to accelerate this research, from knockout to library screening.
References
- 1. Ihara K et al.. 2022. Importance of transmembrane helix 4 of l-alanine exporter AlaE in oligomer formation and substrate export activity in Escherichia coli.. Microbiology (Reading) 168(3) PMID: 35275050
- 2. Štafl K et al.. 2024. Receptor usage of Syncytin-1: ASCT2, but not ASCT1, is a functional receptor and effector of cell fusion in the human placenta.. Proc Natl Acad Sci U S A 121(44):e2407519121 PMID: 39432789
- 3. Pichoff S et al.. 2019. Roles of FtsEX in cell division.. Res Microbiol 170(8):374-380 PMID: 31376483
- 4. García-Añoveros J et al.. 2014. TRPML2 and mucolipin evolution.. Handb Exp Pharmacol 222:647-58 PMID: 24756724
- 5. Suzuki S et al.. 2016. R76 in transmembrane domain 3 of the aspartate:alanine transporter AspT is involved in substrate transport.. Biosci Biotechnol Biochem 80(4):744-7 PMID: 26849958
- 6. Lindt KA et al.. 2024. Interdomain communication in a homodimeric ABC transporter.. J Biol Chem 300(7):107440 PMID: 38844133
- 7. Kim S et al.. 2017. Impact of charged amino acid substitution in the transmembrane domain of L-alanine exporter, AlaE, of Escherichia coli on the L-alanine export.. Arch Microbiol 199(1):105-114 PMID: 27572251
- 8. Sanchez VB et al.. 2019. Transmembrane 163 (TMEM163) protein effluxes zinc.. Arch Biochem Biophys 677:108166 PMID: 31697912
