GO:1903988 iron ion export across plasma membrane: Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1903988 describes the directed movement of iron ions from inside a cell, across the plasma membrane, into the extracellular region.
• Iron export across the plasma membrane is essential for systemic iron homeostasis and is mediated by the ferrous iron exporter ferroportin (SLC40A1/FPN1) in mammals.
• The process is tightly regulated by the iron-regulatory hormone hepcidin, which binds ferroportin and triggers its internalization and degradation.
• DMT1 (SLC11A2) and ferroportin (SLC40A1) are coordinately regulated in intestinal enterocytes to balance dietary iron absorption and export [2,5].
• Nramp1 (SLC11A1) is a structurally and functionally related transporter that mediates phagosomal iron efflux, highlighting evolutionary conservation of iron export mechanisms.
• Dysregulation of iron export is linked to iron overload disorders, anemia of inflammation, and altered iron handling in inflammatory bowel disease [1,5].
Description
Iron ion export across the plasma membrane (GO:1903988) is a biological process defined as the directed movement of iron ions from inside a cell, across the plasma membrane, and into the extracellular region. This process is a cornerstone of systemic iron homeostasis, as it determines how much iron enters the circulation from dietary sources and from body stores. In mammals, the principal mediator of iron export is ferroportin (SLC40A1/FPN1), which transports ferrous iron (Fe2+) out of cells such as intestinal enterocytes, macrophages, and hepatocytes. The exported iron is subsequently oxidized by hephaestin or ceruloplasmin and loaded onto transferrin for distribution throughout the body. Research on iron ion export across the plasma membrane is critical because imbalances in this process underlie a wide range of human diseases, including hereditary hemochromatosis, ferroportin disease, and anemia of inflammation. The process is also dynamically regulated at the transcriptional and post-translational levels, with the hormone hepcidin playing a central role in controlling ferroportin stability. In intestinal epithelial cells, the coordinated expression of the apical importer DMT1 and the basolateral exporter ferroportin ensures efficient dietary iron absorption and export [2,5]. Beyond mammals, iron export mechanisms are conserved across evolution, as exemplified by Dictyostelium Nramp1, which is structurally and functionally similar to mammalian DMT1 and mediates phagosomal iron efflux. In plants, ATP-binding cassette (ABC) transporters contribute to iron homeostasis under abiotic and biotic stresses, although the specific plasma membrane iron export machinery differs from that of metazoans. Understanding the molecular players and regulatory logic of GO:1903988 provides a foundation for developing therapeutic strategies targeting iron-related disorders.
iron ion export across plasma membrane At A Glance
| GO ID | GO:1903988 |
|---|---|
| GO term | iron ion export across plasma membrane |
| Ontology | biological_process |
| Synonym | ferrous iron export; ferrous iron export across plasma membrane; iron(2+) export; iron cation export |
| Major function | Export of iron ions from the cytosol to the extracellular region across the plasma membrane |
| Directionality | Inside of cell to extracellular region |
| Representative transporter | Ferroportin (SLC40A1/FPN1) in mammals |
| Regulatory hormone | Hepcidin, which binds ferroportin and induces its degradation |
| Related process | Intestinal iron absorption, macrophage iron recycling, placental iron transfer |
What Is GO:1903988?
GO:1903988 (iron ion export across plasma membrane) is the biological process in which iron ions are transported from the intracellular compartment, across the plasma membrane, and into the extracellular space. This is a directed, energy-dependent or gradient-driven movement that reduces intracellular iron levels and increases extracellular iron availability. The process is synonymous with ferrous iron export, ferrous iron export across plasma membrane, iron(2+) export, and iron cation export. It is distinct from intracellular iron trafficking or iron import, as it specifically requires crossing the plasma membrane to the outside of the cell.
Why Is iron ion export across plasma membrane Important in Cell Biology?
Iron ion export across the plasma membrane is essential for maintaining systemic iron balance because there is no active physiological mechanism for iron excretion in mammals. All iron loss occurs through passive shedding of cells and blood loss, so the amount of iron exported from enterocytes, macrophages, and hepatocytes directly determines circulating iron levels. Dysregulation of this process leads to iron overload or iron restriction, both of which have severe clinical consequences. For researchers, understanding GO:1903988 provides mechanistic insight into diseases such as hereditary hemochromatosis, ferroportin disease, and anemia of inflammation, and offers targets for therapeutic modulation of iron status.
• Controls systemic iron availability by mediating iron efflux from intestinal enterocytes into the bloodstream.
• Enables macrophage iron recycling, which supplies most of the iron used for erythropoiesis.
• Is the direct target of hepcidin, the master regulator of iron homeostasis.
• Dysfunction causes ferroportin disease, an autosomal dominant iron overload disorder.
• Contributes to anemia of inflammation through hepcidin-mediated ferroportin degradation.
• Is altered in inflammatory bowel disease, where increased DMT1 and FPN1 expression enhances iron absorption and export.
• Shares evolutionary origins with Nramp1-mediated phagosomal iron efflux in Dictyostelium.
• In plants, ABC transporters contribute to iron homeostasis under stress, indicating broader relevance of iron transport mechanisms.
• Provides a therapeutic target for chelation-independent modulation of iron overload.
• Is a key determinant of dietary iron absorption efficiency, which varies with physiological state and diet.
What Happens During iron ion export across plasma membrane?
Uptake of iron into the cytosol
In simple terms: Iron first gets into the cell before it can be exported.
In intestinal enterocytes, dietary iron is taken up across the apical membrane by DMT1 (SLC11A2) after reduction from Fe3+ to Fe2+. In macrophages, iron derived from phagocytosed erythrocytes is released into the cytosol through Nramp1 (SLC11A1) or other transporters. This cytosolic iron pool is the substrate for subsequent export across the basolateral or plasma membrane. The size and redox state of this pool are critical for determining export efficiency.
Recognition and transport by ferroportin
In simple terms: A dedicated exporter protein picks up iron and pushes it out of the cell.
Ferroportin (SLC40A1/FPN1) is the only known mammalian iron exporter that moves Fe2+ from the cytosol across the plasma membrane to the extracellular space. It is highly expressed in enterocytes, macrophages, and hepatocytes. Ferroportin functions as a multimers and its transport activity is coupled to the oxidation of Fe2+ to Fe3+ by hephaestin or ceruloplasmin, which facilitates loading onto transferrin. In inflammatory bowel disease, increased FPN1 expression in colonocytes is associated with enhanced iron absorption and export.
Post-translational regulation by hepcidin
In simple terms: A hormone called hepcidin can bind the exporter and cause it to be destroyed.
Hepcidin, a liver-derived peptide hormone, binds to ferroportin on the cell surface, inducing its internalization, ubiquitination, and degradation in lysosomes. This mechanism reduces iron export from enterocytes and macrophages, lowering circulating iron levels. Hepcidin expression is increased by inflammation and iron loading, and decreased by erythropoietic demand and hypoxia. This regulatory loop is central to the pathophysiology of anemia of inflammation and iron overload disorders.
Extracellular iron oxidation and transferrin loading
In simple terms: Once outside, iron is oxidized and carried away by a transport protein.
After export, Fe2+ is oxidized to Fe3+ by membrane-bound hephaestin in enterocytes or by circulating ceruloplasmin. The resulting Fe3+ is bound by transferrin, which delivers iron to tissues expressing transferrin receptor 1. This oxidation step is essential because transferrin only binds ferric iron with high affinity. In the absence of adequate oxidation, iron export is impaired, leading to cellular iron retention.
Coordination with iron import and storage
In simple terms: Export is balanced with import and storage to keep cellular iron levels stable.
Iron export across the plasma membrane is coordinately regulated with iron import (via DMT1 and TfR1) and storage (via ferritin) to maintain cellular iron homeostasis. In enterocytes, DMT1 and ferroportin expression are increased in conditions of high iron demand, such as ulcerative colitis, to enhance absorption and export. The iron regulatory proteins IRP1 and IRP2 modulate the stability of mRNAs encoding these transporters in response to cytosolic iron levels.
Key Genes Involved in GO:1903988 iron ion export across plasma membrane
The following genes and proteins are experimentally implicated in iron ion export across the plasma membrane or in closely related iron transport processes.
| Gene | Major Role | Research Relevance |
|---|---|---|
| SLC40A1 (FPN1) | Ferroportin, the principal mammalian iron exporter across the plasma membrane | Central to systemic iron homeostasis; mutations cause ferroportin disease |
| HAMP | Hepcidin, the hormone that binds ferroportin and induces its degradation | Master regulator of iron export; dysregulated in anemia of inflammation |
| SLC11A2 (DMT1) | Apical iron importer in enterocytes; provides cytosolic iron for export | Coordinated with ferroportin in intestinal iron absorption [2,5] |
| SLC11A1 (NRAMP1) | Phagosomal iron efflux transporter; structurally similar to DMT1 | Mediates iron export from phagosomes in macrophages |
| HFE | Regulates hepcidin expression in response to transferrin saturation | Mutations cause hereditary hemochromatosis |
| TFR2 | Transferrin receptor 2; senses iron status and regulates hepcidin | Involved in iron sensing and hepcidin regulation |
| HJV (HFE2) | Hemojuvelin; BMP co-receptor that regulates hepcidin | Mutations cause juvenile hemochromatosis |
| BMP6 | Bone morphogenetic protein 6; induces hepcidin transcription | Key regulator of iron export via hepcidin |
| CP (ceruloplasmin) | Ferroxidase that oxidizes Fe2+ after export for transferrin loading | Facilitates iron export and distribution |
| HEPH (hephaestin) | Intestinal ferroxidase that oxidizes Fe2+ after ferroportin-mediated export | Essential for efficient dietary iron export |
| TF (transferrin) | Binds ferric iron in circulation after export | Delivers exported iron to tissues |
| ABC transporters (plant) | Contribute to iron homeostasis under abiotic and biotic stresses | Plant iron transport mechanisms |
| Nramp1 (Dictyostelium) | Mediates phagosomal iron efflux | Evolutionary model for iron export |
| Ferritin (FTL/FTN) | Stores intracellular iron, limiting availability for export | Regulates cytosolic iron pool |
| IRP1/IRP2 (ACO1/IREB2) | Regulate mRNA stability of iron transporters in response to iron levels | Post-transcriptional control of iron export machinery |
| ZIP transporters | Zinc and iron transporters in bacteria and plants | Related metal transport mechanisms |
| Apple rootstock genes | Iron absorption differences under alkaline conditions | Plant iron transport and stress responses |
How Is iron ion export across plasma membrane Regulated?
Iron ion export across the plasma membrane is regulated at multiple levels. Systemically, the hormone hepcidin binds ferroportin and triggers its internalization and degradation, thereby reducing iron export from enterocytes and macrophages. Hepcidin expression is induced by iron loading, inflammation, and BMP6 signaling, and suppressed by erythropoietic demand and hypoxia. At the cellular level, iron regulatory proteins (IRP1 and IRP2) modulate the stability of mRNAs encoding DMT1 and ferroportin in response to cytosolic iron levels. In intestinal cells, DMT1 and FPN1 expression is coordinately increased in ulcerative colitis, enhancing iron absorption and export. Additionally, ferroxidases such as hephaestin and ceruloplasmin facilitate the oxidation of exported Fe2+, which is necessary for transferrin loading and efficient export.
iron ion export across plasma membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| SLC40A1 | Ferroportin disease; iron overload | Knock-in mouse models of SLC40A1 mutations; patient-derived iPSCs |
| HAMP | Anemia of inflammation; iron restriction | Hepcidin knockout or transgenic mice; inflammation models |
| HFE | Hereditary hemochromatosis | HFE knockout mice; iron-loaded diet models |
| SLC11A2 | Iron deficiency anemia; altered intestinal absorption | Intestine-specific DMT1 knockout mice |
| SLC11A1 | Mycobacterial susceptibility; phagosomal iron efflux | Nramp1 knockout mice; macrophage infection models |
Ferroportin disease and hereditary hemochromatosis
Mutations in SLC40A1 (ferroportin) cause ferroportin disease, an autosomal dominant disorder characterized by iron overload due to impaired iron export from macrophages and enterocytes. Loss-of-function mutations in HFE, TFR2, or HJV lead to hereditary hemochromatosis by reducing hepcidin expression, which in turn increases ferroportin-mediated iron export and causes excessive intestinal iron absorption. These conditions highlight the critical role of GO:1903988 in systemic iron balance.
Anemia of inflammation
Inflammatory cytokines such as IL-6 induce hepcidin expression, which binds ferroportin and induces its degradation, thereby reducing iron export from enterocytes and macrophages. This leads to hypoferremia and restricted erythropoiesis, contributing to anemia of inflammation. The process of iron ion export across the plasma membrane is therefore a central therapeutic target in inflammatory anemias.
Inflammatory bowel disease
In ulcerative colitis, increased expression of DMT1 and FPN1 in the colon is associated with enhanced iron absorption and export, potentially contributing to altered iron status in patients. This demonstrates that iron export across the plasma membrane is dynamically regulated in response to inflammatory conditions in the gut.
Neurodegeneration and iron dyshomeostasis
Although direct evidence for GO:1903988 in neurodegeneration is limited in the provided citations, iron accumulation is a feature of several neurodegenerative disorders. Ferroportin is expressed in the brain, and its dysfunction may contribute to regional iron overload. Further research is needed to establish causal links between plasma membrane iron export and neurodegeneration.
From iron ion export across plasma membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of SLC40A1 impair cellular iron export? | SLC40A1 knockout cell lines (e.g., HepG2, Caco-2) generated by CRISPR |
| Does a specific SLC40A1 mutation cause ferroportin disease? | Point-mutation knock-in cell lines or mouse models |
| Can a tagged ferroportin be used to track export dynamics? | Knock-in of fluorescent or epitope tags at the endogenous SLC40A1 locus |
| Does overexpression of ferroportin reduce cellular iron loading? | SLC40A1 overexpression cell lines |
| Which genes regulate hepcidin expression? | CRISPR library screening in hepatocyte cell lines |
| How does DMT1 coordinate with ferroportin in enterocytes? | Intestinal organoids with inducible knockout of SLC11A2 or SLC40A1 |
How to Study the iron ion export across plasma membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| RNA-seq | Transcript levels of iron transport genes | Comparing iron export gene expression across conditions [5,7] |
| qPCR | Relative mRNA expression | Validating SLC40A1, SLC11A2, HAMP changes |
| Western blot | Protein levels of ferroportin, DMT1, hepcidin | Assessing regulation by iron or inflammation |
| 55Fe efflux assay | Rate of iron export from cells | Functional validation of ferroportin activity |
| Ferroxidase assay | Oxidation of Fe2+ to Fe3+ | Measuring hephaestin/ceruloplasmin activity |
| Fluorescence microscopy | Subcellular localization of tagged transporters | Tracking ferroportin internalization [1,6] |
| CRISPR knockout screening | Genes required for iron export or hepcidin regulation | Unbiased discovery of novel regulators |
| Metabolomics | Iron-related metabolites and oxidative stress markers | Linking iron export to metabolic pathways |
Transcriptomic analysis of iron transport genes
RNA-seq can quantify expression of SLC40A1, SLC11A2, HAMP, and other iron-related genes across cell types and conditions. In ulcerative colitis, RNA-seq and qPCR revealed increased DMT1 and FPN1 expression in colon, linking transcriptional changes to enhanced iron absorption and export. Transcriptome analysis in apple rootstocks under alkaline conditions identified genes associated with iron absorption differences, demonstrating the utility of RNA-seq in studying iron transport across species.
Proteomic and biochemical assays for iron export
Western blotting and immunodetection can measure ferroportin protein levels and its regulation by hepcidin. Ferroxidase activity assays measure the oxidation of Fe2+ to Fe3+ by hephaestin or ceruloplasmin, which is coupled to iron export. Radioactive iron (55Fe or 59Fe) efflux assays directly quantify iron export across the plasma membrane in cultured cells.
Imaging and subcellular localization
Fluorescence microscopy of tagged ferroportin can reveal its plasma membrane localization and internalization in response to hepcidin. In Dictyostelium, imaging of Nramp1-GFP showed its localization to phagosomes and its role in iron efflux. These approaches are valuable for studying the spatial dynamics of iron export.
Genetic screens and CRISPR libraries
CRISPR knockout library screening can identify genes that regulate iron export or hepcidin expression. For example, genome-wide screens in hepatocytes could uncover novel regulators of HAMP transcription. Such screens complement targeted studies of known iron transporters and provide unbiased discovery of new components in the iron export pathway.
How CRISPR Can Be Used to Study GO:1903988 iron ion export across plasma membrane
Knockout
CRISPR knockout of SLC40A1 in cell lines such as HepG2 or Caco-2 can abolish ferroportin-mediated iron export, leading to cellular iron retention and increased ferritin expression. Knockout of HAMP in hepatocytes would reduce hepcidin production, increasing ferroportin stability and iron export. These models are essential for dissecting the causal role of specific genes in GO:1903988.
Point Mutation
Point mutations in SLC40A1 identified in ferroportin disease patients can be introduced into cell lines using CRISPR base editing or homology-directed repair to study their effects on iron export activity and hepcidin responsiveness. Such models help distinguish loss-of-function from gain-of-function mechanisms.
Knock-in
Knock-in of fluorescent tags (e.g., GFP) or epitope tags at the endogenous SLC40A1 locus allows real-time tracking of ferroportin trafficking and hepcidin-induced degradation. Similarly, knock-in of reporter genes under the HAMP promoter enables monitoring of hepcidin regulation in live cells.
Overexpression
Overexpression of SLC40A1 in cell lines can enhance iron export and reduce cellular iron loading, providing a gain-of-function model to study export capacity and its effects on iron-dependent processes. Overexpression of hepcidin or its regulators can also modulate iron export indirectly.
How EDITGENE Supports iron ion export across plasma membrane Research
Researchers studying iron ion export across plasma membrane-related genes often need to determine whether a candidate gene is causally involved in iron transport, how mutations affect transporter function, and whether modulating its expression alters cellular iron status. EDITGENE provides a comprehensive suite of CRISPR-based services to address these questions with precision and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for iron ion export across plasma membrane research.
Frequently Asked Questions About iron ion export across plasma membrane
What is GO:1903988?
GO:1903988 is the Gene Ontology term for iron ion export across plasma membrane, defined as the directed movement of iron ions from inside a cell, across the plasma membrane, and into the extracellular region.
What genes are involved in iron ion export across plasma membrane?
Key genes include SLC40A1 (ferroportin), HAMP (hepcidin), SLC11A2 (DMT1), SLC11A1 (Nramp1), HFE, TFR2, HJV, BMP6, CP (ceruloplasmin), and HEPH (hephaestin) [1,2,5,6].
How is iron exported from cells?
Iron is exported primarily by ferroportin (SLC40A1), which transports Fe2+ across the plasma membrane; the iron is then oxidized by hephaestin or ceruloplasmin and loaded onto transferrin.
What is the role of hepcidin in iron export?
Hepcidin binds ferroportin and induces its internalization and degradation, thereby reducing iron export from enterocytes and macrophages.
Which diseases are linked to defective iron export?
Ferroportin disease, hereditary hemochromatosis, anemia of inflammation, and altered iron status in inflammatory bowel disease are linked to defective or dysregulated iron export [1,5].
How can I study iron ion export in the lab?
Common methods include 55Fe efflux assays, Western blotting for ferroportin, RNA-seq, fluorescence microscopy of tagged transporters, and CRISPR knockout screens [1,5,6].
What is the difference between DMT1 and ferroportin?
DMT1 (SLC11A2) imports iron into cells across the apical membrane, while ferroportin (SLC40A1) exports iron across the basolateral or plasma membrane [2,5].
Is iron export conserved in evolution?
Yes, Nramp1 in Dictyostelium is structurally and functionally similar to mammalian DMT1 and mediates phagosomal iron efflux, indicating conservation of iron transport mechanisms.
Can CRISPR be used to study iron export?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect the function of genes involved in iron export across the plasma membrane.
What are the synonyms for GO:1903988?
Synonyms include ferrous iron export, ferrous iron export across plasma membrane, iron(2+) export, and iron cation export.
Conclusion
Iron ion export across the plasma membrane (GO:1903988) is a fundamental biological process that controls systemic iron availability and cellular iron homeostasis. The principal mediator, ferroportin, is regulated by hepcidin and coordinated with iron import and storage pathways. Dysregulation of this process causes iron overload disorders, anemia of inflammation, and contributes to altered iron handling in inflammatory bowel disease [1,5]. Continued research using CRISPR-based models and multi-omics approaches will further elucidate the molecular mechanisms and therapeutic potential of targeting iron export.
References
- 1. Anderson GJ et al.. 2017. Current understanding of iron homeostasis.. Am J Clin Nutr 106(Suppl 6):1559S-1566S PMID: 29070551
- 2. Fuqua BK et al.. 2012. Intestinal iron absorption.. J Trace Elem Med Biol 26(2-3):115-9 PMID: 22575541
- 3. Hantke K. 2001. Bacterial zinc transporters and regulators.. Biometals 14(3-4):239-49 PMID: 11831459
- 4. Dahuja A et al.. 2021. Role of ATP-binding cassette transporters in maintaining plant homeostasis under abiotic and biotic stresses.. Physiol Plant 171(4):785-801 PMID: 33280130
- 5. Minor EA et al.. 2020. Increased DMT1 and FPN1 expression with enhanced iron absorption in ulcerative colitis human colon.. Am J Physiol Cell Physiol 318(2):C263-C271 PMID: 31721611
- 6. Buracco S et al.. 2015. Dictyostelium Nramp1, which is structurally and functionally similar to mammalian DMT1 transporter, mediates phagosomal iron efflux.. J Cell Sci 128(17):3304-16 PMID: 26208637
- 7. Li Y et al.. 2025. Transcriptome and metabolome analysis reveal the mechanisms of iron absorption differences in apple rootstocks under alkaline condition.. Physiol Plant 177(1):e70134 PMID: 39994109
