GO:0015824 proline transport: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015824 proline transport describes the directed movement of proline (pyrrolidine-2-carboxylic acid) into, out of, or within a cell, or between cells, via transporters or pores.
• Proline transport is essential for retinal health, where it supports the visual cycle and protects against oxidative stress.
• In plants, proline transport is critical for development, stress responses, and nitrogen distribution.
• Mitochondrial proline transport is mediated by specific carriers and is linked to energy metabolism and redox balance.
• Proline transporters are found across species, from yeast (PUT4, GAP1) to protozoan parasites (Leishmania, Trypanosoma) and mammals (SLC36A1, SLC6A20).
• Dysregulation of proline transport is implicated in retinal degeneration, cancer, and parasitic infections.
Description
Proline transport (GO:0015824) is the biological process by which the amino acid proline is moved across cellular membranes or between cellular compartments. This process is fundamental for maintaining intracellular proline homeostasis, which is required for protein synthesis, cellular redox balance, and energy metabolism. Proline is unique among amino acids due to its cyclic structure, which influences its transport kinetics and its role in stress responses. In retinal health, proline transport is critical for the visual cycle and protection against oxidative damage, and its disruption is linked to retinal degeneration. In plants, proline transport supports development and stress tolerance, including drought and salt stress. Mitochondrial proline transport is essential for energy production and redox regulation, with specific carriers facilitating its uptake. Given its broad importance, proline transport is a subject of intense research across cell biology, neuroscience, and microbiology.
proline transport At A Glance
| GO ID | GO:0015824 |
|---|---|
| GO term | proline transport |
| Ontology | biological_process |
| Synonym | L-proline transport |
| Major function | Directed movement of proline across membranes or between cells |
| Substrates | L-proline (pyrrolidine-2-carboxylic acid) |
| Cellular locations | Plasma membrane, mitochondrial membrane, intracellular vesicles |
| Related processes | Proline metabolism, amino acid homeostasis, oxidative stress response |
| Key transporters | SLC36A1, SLC6A20, PUT4, GAP1, proline permease |
What Is GO:0015824?
According to the Gene Ontology, GO:0015824 proline transport is defined as the directed movement of proline, pyrrolidine-2-carboxylic acid, 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 proline across biological membranes, which can occur via passive diffusion or active transport mechanisms. The synonym L-proline transport is also used. This term is a biological process and is distinct from proline metabolism, although the two are functionally linked.
Why Is proline transport Important in Cell Biology?
Proline transport is vital for cellular function because proline serves as a building block for proteins, a key osmolyte, and a regulator of redox balance. Defects in proline transport are associated with retinal degeneration, where proline uptake is necessary for the visual cycle and protection against oxidative stress. In plants, proline transport is essential for development and stress responses, including drought and salt tolerance. Mitochondrial proline transport supports energy metabolism and is linked to the regulation of reactive oxygen species. In protozoan parasites, proline transport is critical for survival and virulence, making it a potential drug target. Thus, understanding proline transport mechanisms has broad implications for human health, agriculture, and infectious disease.
• Proline transport maintains intracellular proline levels required for protein synthesis and cell growth.
• It protects retinal cells from oxidative stress and supports the visual cycle.
• In plants, it facilitates nitrogen distribution and osmotic adjustment during stress.
• Mitochondrial proline transport is linked to energy production and redox homeostasis.
• Proline transporters are essential for the survival of protozoan parasites like Leishmania and Trypanosoma.
• Maternal proline supplementation enhances fetal survival and placental nutrient transport in mice.
• Dysregulated proline transport is implicated in cancer metabolism and metastasis.
• Proline transport is a potential target for antiparasitic drugs.
• It plays a role in yeast nitrogen utilization and stress response.
• Understanding proline transport can inform therapies for retinal diseases and metabolic disorders.
What Happens During proline transport?
Substrate recognition and binding
In simple terms: The transporter recognizes proline and binds it specifically.
Proline transporters exhibit high specificity for L-proline, often distinguishing it from other amino acids based on its unique cyclic structure. In Saccharomyces cerevisiae, the proline permease PUT4 is highly specific for proline and mediates its uptake under nitrogen-limiting conditions. In Trypanosoma cruzi, proline transport is mediated by a specific active transport system that is saturable and energy-dependent. Similarly, in Leishmania donovani, proline transport is developmentally regulated, with stage-specific expression of transporters.
Translocation across the membrane
In simple terms: The transporter moves proline across the cell membrane.
After binding, the transporter undergoes conformational changes to translocate proline across the lipid bilayer. This process can be driven by ion gradients or ATP hydrolysis. In rat kidney mitochondria, proline transport is mediated by a specific carrier that is sensitive to inhibitors of mitochondrial transport. In plants, proline transporters such as ProT1 and ProT2 mediate proton-coupled proline uptake. The direction of transport can be inward or outward depending on cellular needs.
Intracellular distribution and compartmentalization
In simple terms: Once inside, proline is moved to where it is needed.
Proline can be transported into mitochondria for energy metabolism or into the cytoplasm for protein synthesis. Mitochondrial proline transport is essential for proline oxidation and ATP production. In retinal cells, proline transport is critical for the visual cycle, where it is used for the synthesis of visual pigments. In plants, proline is transported into chloroplasts and other organelles for stress responses.
Regulation of transport activity
In simple terms: The cell controls how much proline is moved and when.
Proline transport is regulated at multiple levels, including transcriptional control of transporter genes and post-translational modifications. In Leishmania donovani, proline transport activity varies with developmental stage, with higher activity in promastigotes. In Saccharomyces cerevisiae, PUT4 expression is induced under nitrogen starvation. In mammals, proline transport in the retina is regulated by osmotic stress and oxidative conditions.
Integration with metabolism and signaling
In simple terms: Proline transport is linked to other cellular processes.
Proline transport is tightly coupled to proline metabolism, as transported proline can be catabolized to glutamate or used for collagen synthesis. In mitochondria, proline transport feeds into the proline dehydrogenase pathway, influencing redox balance. In plants, proline transport is integrated with nitrogen assimilation and stress signaling. In parasites, proline transport supports energy metabolism and osmoregulation.
Key Genes Involved in GO:0015824 proline transport
The following genes and proteins are key players in proline transport across various organisms, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC36A1 | Proton-coupled amino acid transporter that transports proline | Implicated in retinal proline transport and oxidative stress protection |
| SLC6A20 | Sodium-dependent proline transporter | Expressed in kidney and intestine; involved in proline homeostasis |
| PUT4 | Proline permease in Saccharomyces cerevisiae | Model for studying proline uptake and nitrogen regulation |
| GAP1 | General amino acid permease in yeast | Transports proline and other amino acids; studied for transport specificity |
| ProT1 | Plant proline transporter | Mediates proline uptake in roots and flowers; involved in stress responses |
| ProT2 | Plant proline transporter | Expressed in pollen and involved in development |
| ProT3 | Plant proline transporter | Functions in proline transport in leaves and stems |
| LdProT | Leishmania donovani proline transporter | Developmentally regulated; potential drug target |
| TcProT | Trypanosoma cruzi proline transporter | Active transport system; essential for parasite survival |
| PRODH | Proline dehydrogenase | Mitochondrial enzyme that oxidizes proline; linked to transport |
| P5CS | Delta-1-pyrroline-5-carboxylate synthetase | Key enzyme in proline biosynthesis; coordinates with transport |
| P5CR | Pyrroline-5-carboxylate reductase | Catalyzes proline synthesis; interacts with transport pathways |
| OAT | Ornithine aminotransferase | Involved in proline synthesis and degradation; affects transport demand |
| SLC38A2 | Sodium-coupled neutral amino acid transporter | Transports proline in some tissues; role in cancer metabolism |
| SLC7A5 | L-type amino acid transporter | Transports proline and other large amino acids; implicated in cancer |
| SLC3A2 | Heavy chain of amino acid transporters | Partners with SLC7A5 to transport proline |
| mTOR | Serine/threonine kinase | Regulates proline transport via nutrient signaling |
| ATF4 | Transcription factor | Regulates proline transporter expression under stress |
How Is proline transport Regulated?
Proline transport is regulated at transcriptional, post-transcriptional, and post-translational levels. In Saccharomyces cerevisiae, the proline permease PUT4 is induced under nitrogen starvation and repressed by rich nitrogen sources. In Leishmania donovani, proline transport activity is developmentally regulated, with higher activity in promastigotes compared to amastigotes. In mammals, proline transport in the retina is regulated by osmotic stress and oxidative conditions, with transporters like SLC36A1 and SLC6A20 showing altered expression. Mitochondrial proline transport is regulated by the availability of substrates and the redox state of the cell. Additionally, the mTOR signaling pathway influences proline transport by modulating the expression of amino acid transporters.
proline transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC36A1 | Retinal degeneration | Knockout mouse, retinal pigment epithelium cells |
| SLC6A20 | Retinal degeneration, hyperprolinemia | Knockout mouse, patient-derived fibroblasts |
| LdProT | Leishmaniasis | Leishmania donovani knockout, macrophage infection model |
| TcProT | Chagas disease | Trypanosoma cruzi knockout, cardiomyocyte infection model |
| SLC7A5 | Cancer (various) | Cancer cell lines, xenograft mouse models |
Proline transport in retinal degeneration
Proline transport is essential for retinal health, where it supports the visual cycle and protects against oxidative stress. Mutations or dysregulation of proline transporters such as SLC36A1 and SLC6A20 have been linked to retinal degeneration and impaired vision. Proline uptake in retinal pigment epithelium is critical for the synthesis of visual pigments and for maintaining cellular redox balance. Studies in animal models show that proline supplementation can improve retinal function, suggesting that enhancing proline transport may be therapeutic.
Proline transport in parasitic infections
Proline transport is critical for the survival of protozoan parasites like Leishmania donovani and Trypanosoma cruzi. These parasites rely on proline as a major energy source, and their transporters are developmentally regulated. Inhibition of proline transport reduces parasite viability, making these transporters attractive drug targets. Research into the structure and function of parasite proline transporters could lead to new antiparasitic therapies.
Proline transport in cancer metabolism
Cancer cells often reprogram amino acid transport to support rapid growth. Proline transporters such as SLC36A1 and SLC6A20 are overexpressed in some cancers, contributing to proline uptake and metabolism. Proline is used for protein synthesis and collagen production, which are essential for tumor growth and metastasis. Targeting proline transport may be a novel strategy for cancer therapy.
Proline transport in plant stress responses
In plants, proline transport is crucial for osmotic adjustment and stress tolerance. Proline transporters like ProT1, ProT2, and ProT3 are upregulated under drought and salt stress, facilitating proline accumulation in tissues. This accumulation helps maintain cell turgor and protects proteins and membranes. Understanding proline transport in plants can inform crop improvement for stress resistance.
From proline transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of SLC36A1 in retinal proline transport? | SLC36A1 knockout mouse, retinal pigment epithelium cells |
| How does PUT4 regulate proline uptake in yeast? | PUT4 knockout yeast, nitrogen starvation conditions |
| Does proline transport affect parasite survival? | Leishmania donovani proline transporter knockout, macrophage infection |
| What is the impact of proline transport on cancer growth? | SLC7A5 overexpression in cancer cell lines, xenograft models |
| How does proline transport respond to osmotic stress in plants? | ProT1/ProT2 knockout Arabidopsis, salt stress treatments |
| Can proline supplementation improve fetal survival? | Maternal proline supplementation in mice, placental transport assays |
How to Study the proline transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Radiolabeled proline uptake | Transport activity | Characterizing transporter kinetics in yeast, parasites, and mammalian cells |
| CRISPR-Cas9 knockout | Loss-of-function phenotype | Studying the role of specific transporters in disease models |
| RNA-seq | Gene expression levels | Identifying transporters upregulated under stress or disease |
| Western blot | Protein expression | Validating transporter protein levels |
| Immunofluorescence | Subcellular localization | Determining where transporters localize in cells |
| Patch clamp | Electrogenic transport | Measuring ion-coupled proline transport |
| Proteomics | Protein interactions | Identifying binding partners of proline transporters |
| Metabolomics | Proline levels | Assessing the impact of transport on cellular metabolism |
Transport assays
Radiolabeled proline uptake assays are widely used to measure proline transport activity in cells and isolated organelles. For example, [3H]-proline uptake in Saccharomyces cerevisiae can quantify PUT4 activity. In Leishmania donovani, proline transport is measured using radioisotope flux in promastigotes and amastigotes. These assays are essential for characterizing transporter kinetics and specificity.
Genetic knockout and knockdown
CRISPR-Cas9 knockout of proline transporter genes in model organisms such as yeast, mice, and parasites allows researchers to study loss-of-function phenotypes. For instance, PUT4 knockout in yeast abolishes proline uptake. In mice, knockout of SLC36A1 leads to retinal dysfunction. These models are crucial for establishing causality.
Expression analysis
RNA-seq and qPCR are used to measure the expression of proline transporter genes under different conditions. In plants, ProT1 and ProT2 expression is induced by drought stress. In Leishmania, stage-specific expression of proline transporters is observed. These methods help identify regulatory mechanisms.
Structural biology
Crystal structures and cryo-EM of proline transporters provide insights into substrate binding and translocation mechanisms. Although structures of some proline transporters are available, many remain to be solved. Structural studies can guide drug design targeting parasite transporters.
How CRISPR Can Be Used to Study GO:0015824 proline transport
Knockout
CRISPR-Cas9 knockout of proline transporter genes is a powerful approach to study their function. For example, knocking out PUT4 in Saccharomyces cerevisiae abolishes proline uptake, confirming its role as a proline permease. In mice, knockout of SLC36A1 results in retinal degeneration, demonstrating its importance in vision. Knockout models are essential for establishing causality between transporter genes and phenotypes.
Point Mutation
Point mutations can be introduced into proline transporter genes to study structure-function relationships. For instance, mutating residues in the substrate-binding pocket of PUT4 can alter proline specificity. In human SLC36A1, point mutations identified in patients with retinal degeneration can be modeled in cell lines to assess transport activity. These models help pinpoint critical amino acids for transport.
Knock-in
Knock-in of tagged proline transporters (e.g., GFP or HA) allows for real-time visualization and localization studies. In Leishmania donovani, knock-in of a tagged proline transporter can reveal its developmental stage-specific expression. In plants, knock-in of ProT1-GFP can show its localization in root cells. These models are valuable for understanding transporter dynamics.
Overexpression
Overexpression of proline transporters can enhance proline uptake and alter cellular phenotypes. In cancer cells, overexpression of SLC7A5 increases proline transport and promotes growth. In plants, overexpression of ProT1 improves drought tolerance by increasing proline accumulation. Overexpression models are useful for gain-of-function studies and for testing therapeutic strategies.
How EDITGENE Supports proline transport Research
Researchers studying proline transport-related genes often need to determine whether a candidate gene is causally involved in a specific phenotype, such as retinal degeneration or parasite survival. This requires precise genetic manipulation, which can be achieved through CRISPR-based knockout, point mutation, knock-in, or overexpression models. EDITGENE provides comprehensive services to generate these models efficiently and reliably.
Contact EDITGENE today to design your custom CRISPR model for proline transport research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| SLC1A4 Knockout HEK293 Cell Line | EDJ-KQ2483 | Human | 6509 | Details Get a Quote |
| SLC6A7 Knockout HEK293 Cell Line | EDJ-KQ3044 | Human | 6534 | Details Get a Quote |
| SLC36A4 Knockout HEK293 Cell Line | EDJ-KQ7657 | Human | 120103 | Details Get a Quote |
| SLC6A15 Knockout HEK293 Cell Line | EDJ-KQ14495 | Human | 55117 | Details Get a Quote |
| SLC6A17 Knockout HEK293 Cell Line | EDJ-KQ15283 | Human | 388662 | Details Get a Quote |
| SLC6A20 Knockout HEK293 Cell Line | EDJ-KQ15286 | Human | 54716 | Details Get a Quote |
| SLC38A2 Knockout HEK293 Cell Line | EDJ-KQ15337 | Human | 54407 | Details Get a Quote |
| SLC3A2 Knockout HEK293 Cell Line | EDJ-KQ17768 | Human | 6520 | Details Get a Quote |
| SLC7A5 Knockout HEK293 Cell Line | EDJ-KQ17900 | Human | 8140 | Details Get a Quote |
| SLC7A5 Knockout HeLa Cell Line | EDC08354 | Human | 8140 | 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 |
| SLC36A4 Knockout A-549 Cell Line | EDJ-KQ33013 | Human | 120103 | Details Get a Quote |
| SLC36A4 Knockout HCT 116 Cell Line | EDJ-KQ33014 | Human | 120103 | Details Get a Quote |
| SLC36A4 Knockout HeLa Cell Line | EDJ-KQ33015 | Human | 120103 | Details Get a Quote |
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Frequently Asked Questions About proline transport
What is proline transport?
Proline transport is the biological process of moving the amino acid proline across cell membranes or between cellular compartments, as defined by GO:0015824.
What genes are involved in proline transport?
Key genes include SLC36A1, SLC6A20, PUT4, GAP1, ProT1, ProT2, ProT3, LdProT, and TcProT, among others.
Why is proline transport important for retinal health?
Proline transport supports the visual cycle and protects retinal cells from oxidative stress; its disruption leads to retinal degeneration.
How is proline transport regulated in yeast?
In Saccharomyces cerevisiae, proline transport is regulated by nitrogen availability, with PUT4 induced under nitrogen starvation.
What diseases are associated with proline transport defects?
Diseases include retinal degeneration, hyperprolinemia, and parasitic infections such as leishmaniasis and Chagas disease.
Can proline transport be targeted for cancer therapy?
Yes, proline transporters like SLC7A5 are overexpressed in some cancers and are potential therapeutic targets.
What methods are used to study proline transport?
Common methods include radiolabeled uptake assays, CRISPR knockout, RNA-seq, and structural biology.
How does proline transport affect plant stress tolerance?
Proline transporters like ProT1 facilitate proline accumulation under drought and salt stress, enhancing tolerance.
What is the role of mitochondrial proline transport?
Mitochondrial proline transport is essential for energy metabolism and redox balance, mediated by specific carriers.
How can CRISPR be used to study proline transport?
CRISPR can create knockout, point mutation, knock-in, and overexpression models to dissect the function of proline transporters.
Conclusion
Proline transport (GO:0015824) is a fundamental biological process with wide-ranging implications for human health, agriculture, and infectious disease. From retinal protection to parasite survival, the mechanisms and regulation of proline transport are critical areas of research. Advances in CRISPR-based models and bioinformatics are accelerating our understanding of these transporters and their roles in disease. Continued investigation promises to uncover new therapeutic targets and strategies.
References
- 1. Du J et al.. 2021. Proline metabolism and transport in retinal health and disease.. Amino Acids 53(12):1789-1806 PMID: 33871679
- 2. Lehmann S et al.. 2010. Proline metabolism and transport in plant development.. Amino Acids 39(4):949-62 PMID: 20204435
- 3. Palmieri F et al.. 2010. Mitochondrial metabolite transport.. Essays Biochem 47:37-52 PMID: 20533899
- 4. Lasko PF et al.. 1981. Proline transport in Saccharomyces cerevisiae.. J Bacteriol 148(1):241-7 PMID: 7026531
- 5. Liu N et al.. 2019. Maternal L-proline supplementation enhances fetal survival, placental development, and nutrient transport in mice†.. Biol Reprod 100(4):1073-1081 PMID: 30418498
- 6. Mazareb S et al.. 1999. Developmental regulation of proline transport in Leishmania donovani.. Exp Parasitol 91(4):341-8 PMID: 10092478
- 7. Silber AM et al.. 2002. Active transport of L-proline in Trypanosoma cruzi.. J Eukaryot Microbiol 49(6):441-6 PMID: 12503677
- 8. Atlante A et al.. 1994. Proline transport in rat kidney mitochondria.. Arch Biochem Biophys 309(1):139-48 PMID: 7906935
