GO:0005372 water transmembrane transporter activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0005372 water transmembrane transporter activity is a molecular function that enables the transfer of water (H2O) from one side of a membrane to the other.
• Aquaporins (AQPs) are the principal protein family mediating this activity, but water permeation has also been demonstrated for other membrane proteins and artificial channels.
• Water transport is not passive background diffusion: it is dynamically regulated and can be measured in living systems by magnetic resonance methods.
• Dysregulated water transport contributes to human disease, including cystic fibrosis, corneal endothelial dysfunction, and tumor proliferation.
• CRISPR knockout, point-mutation, knock-in, and overexpression models allow causal testing of water-transport genes in relevant cell types.
• Studying GO:0005372 requires combining transport assays, imaging, and bioinformatics to distinguish water-specific flux from solute-coupled transport.
Description
Water transmembrane transporter activity (GO:0005372) is defined in QuickGO as the molecular function that enables the transfer of water (H2O) from one side of a membrane to the other. This activity is fundamental to cell volume regulation, epithelial fluid secretion, and brain water homeostasis, and it is experimentally distinguishable from simple lipid-bilayer diffusion by its sensitivity to protein composition and regulation. Researchers study GO:0005372 because water flux across membranes is coupled to neuronal activity, tumor proliferation, and epithelial function, making it a measurable physiological parameter rather than a static property. The function is not limited to aquaporins: artificial transmembrane water channels and engineered water-soluble receptor kinases demonstrate that water permeation can be reconstituted in non-native scaffolds, which is useful for mechanistic dissection. In disease contexts, mutations that alter membrane protein folding and trafficking, as seen in cystic fibrosis, can indirectly affect water and ion transport across epithelia. Therefore, GO:0005372 sits at the intersection of membrane biophysics, cell physiology, and translational research.
water transmembrane transporter activity At A Glance
| GO ID | GO:0005372 |
|---|---|
| GO term | water transmembrane transporter activity |
| Ontology | molecular_function |
| Synonym | none |
| Definition | Enables the transfer of water (H2O) from one side of a membrane to the other. |
| Major function | Mediates water flux across biological membranes |
| Representative proteins | Aquaporins and other water-permeable membrane proteins |
| Related disease examples | Cystic fibrosis, corneal endothelial dysfunction, glioma proliferation |
| Research methods | Water permeability assays, MRI water exchange, CRISPR models |
What Is GO:0005372?
In practical terms, GO:0005372 describes the ability of a membrane-embedded protein or channel to move water molecules across a lipid bilayer, from one compartment to another, without describing a specific gene product. It is a molecular_function term, so it is assigned to proteins that themselves perform water translocation, not to upstream regulators or downstream effectors. The activity can be measured as water permeability, water exchange rate, or transmembrane water flux in cells and tissues.
Why Is water transmembrane transporter activity Important in Cell Biology?
GO:0005372 is important because water movement across membranes is a core determinant of cell volume, epithelial secretion, and tissue water homeostasis, and it can be quantified in vivo using magnetic resonance approaches. In the brain, active transmembrane water cycling is associated with neuronal activity, linking this molecular function to functional imaging signals. In tumors, water-exchange dynamics can map proliferation activity, suggesting that water transport is not merely housekeeping but tracks clinically relevant biology. In epithelia, water transport across corneal endothelial cells and airway epithelia is essential for transparency and fluid balance, and its disruption contributes to disease.
• Water transport maintains cell volume and prevents osmotic stress in all tissues.
• Neuronal activity is coupled to active transmembrane water cycling, which underlies functional MRI contrast.
• Tumor proliferation can be mapped via water-exchange dynamics, linking GO:0005372 to cancer imaging.
• Corneal endothelial cells depend on transmembrane water and urea transport for deturgescence and transparency.
• Cystic fibrosis mutations impair membrane protein function and indirectly disturb epithelial water and ion balance.
• Artificial water channels provide mechanistic proof that water permeation can be engineered.
• Engineered water-soluble receptor kinases retain molecular function, showing water-compatible design principles.
• Mitochondrial uncoupling protein 2 simulations reveal water-related transport behavior in inner membranes.
• L-carnitine biology intersects with membrane transport physiology relevant to water and solute handling.
• CRISPR models enable causal testing of water-transport genes in disease-relevant cells.
What Happens During water transmembrane transporter activity?
Water recognition and membrane entry
In simple terms: Water molecules approach the membrane protein and enter a dedicated pathway.
Water permeation begins when H2O molecules access a protein-lined pore or channel within the membrane. In aquaporin-type pathways, this entry is selective and excludes protons and ions, which is essential for maintaining electrochemical gradients. Artificial transmembrane water channels demonstrate that a defined pore architecture is sufficient to permit water flux across a lipid bilayer.
Translocation across the bilayer
In simple terms: Water passes through the protein channel from one side of the membrane to the other.
Once inside the channel, water molecules move down their chemical potential gradient across the membrane. This translocation step is the defining event of GO:0005372 and can be measured as increased water permeability or water exchange rate. In brain tissue, active transmembrane water cycling is associated with neuronal activity, indicating that translocation is dynamically coupled to cellular state.
Exit and compartment equilibration
In simple terms: Water leaves the channel on the other side and equilibrates between compartments.
After crossing, water exits into the opposite compartment, contributing to osmotic equilibration and volume changes. In corneal endothelial cells, transmembrane water and urea transport contribute to fluid movement required for corneal transparency. In tumors, water-exchange dynamics reflect proliferation activity, suggesting that exit and equilibration are linked to tissue growth.
Regulation by cellular context
In simple terms: The amount of water transport can change depending on the cell's state and signals.
Water transport activity is not fixed; it can be modulated by membrane composition, protein abundance, and cellular signaling. Molecular dynamics simulations of mitochondrial uncoupling protein 2 indicate that membrane protein conformational states influence water-related transport behavior. In disease, mutations that cause protein misfolding and misprocessing, such as in cystic fibrosis, can indirectly alter epithelial water handling.
Key Genes Involved in GO:0005372 water transmembrane transporter activity
The following genes and proteins are experimentally linked to water transmembrane transport or to membrane water permeability in the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| AQP1 | Aquaporin water channel | Prototypical water transmembrane transporter; studied in epithelia and endothelium |
| AQP2 | Aquaporin water channel | Regulated water transport in kidney and epithelial models |
| AQP3 | Aquaporin water/glycerol channel | Water and solute transport in skin and epithelia |
| AQP4 | Aquaporin water channel | Brain water homeostasis and neuronal activity coupling |
| AQP5 | Aquaporin water channel | Secretory epithelia and glandular water transport |
| CFTR | Chloride channel affecting epithelial water balance | Cystic fibrosis mutations impair membrane function and water handling |
| UCP2 | Mitochondrial uncoupling protein | Simulations reveal water-related transport behavior in inner membrane |
| SLC14A1 | Urea transporter | Coupled water and urea transport in corneal endothelium |
| SLC14A2 | Urea transporter | Urea and water transport in kidney and other tissues |
| ART-WC1 | Artificial transmembrane water channel | Proof-of-principle that water permeation can be engineered |
| QTY-kinase | Engineered water-soluble receptor kinase | Demonstrates water-compatible design with intact molecular function |
| Carnitine transporter proteins | Membrane transport of carnitine | Intersects with membrane transport physiology relevant to water handling |
| Glioma proliferation markers | Cell proliferation | Water-exchange MRI maps proliferation activity in gliomas |
| Neuronal activity markers | Neuronal firing | Brain active transmembrane water cycling is associated with neuronal activity |
| Corneal endothelial markers | Corneal deturgescence | Transmembrane water and urea transport in rat corneal endothelial cells |
| CFTR processing chaperones | Protein folding and trafficking | Mutations lead to misfunction and guide therapy in cystic fibrosis |
| Membrane lipid composition factors | Membrane organization | Influence water permeability and protein function |
| Osmotic stress response proteins | Cell volume regulation | Linked to water transport physiology |
How Is water transmembrane transporter activity Regulated?
Water transmembrane transporter activity is regulated at multiple levels. Protein abundance and trafficking determine how much transporter is present at the membrane, as illustrated by cystic fibrosis mutations that cause misfolding and misprocessing of CFTR and indirectly disturb epithelial water and ion balance. Membrane lipid environment and protein conformational states can modulate water-related transport behavior, as shown by molecular dynamics simulations of mitochondrial uncoupling protein 2. Cellular activity state also regulates water cycling: brain active transmembrane water cycling is associated with neuronal activity, indicating dynamic coupling to signaling. In proliferating tumors, water-exchange dynamics track proliferation activity, suggesting regulation by growth-related programs. Finally, water transport can be coupled to solute transport, as in corneal endothelial cells where water and urea transport are measured together.
water transmembrane transporter activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CFTR | Cystic fibrosis; epithelial water and ion imbalance | Knockout or point-mutation airway epithelial cells |
| AQP1 | Corneal endothelial dysfunction; water transport | Knockout corneal endothelial cells |
| AQP4 | Brain water homeostasis; neuronal activity coupling | Knockout astrocytes or neurons with MRI readout |
| UCP2 | Mitochondrial water-related transport | Knockout or overexpression in mitochondrial models |
| Glioma proliferation markers | Tumor growth and water-exchange MRI | Knock-in reporter glioma cells for imaging |
Cystic fibrosis and epithelial water balance
Cystic fibrosis is caused by mutations in CFTR that lead to protein misfunction, and these defects disturb epithelial ion and water handling. Although CFTR is not itself a water transmembrane transporter, its dysfunction alters the osmotic driving forces that depend on water transport activity. Studying water transport in cystic fibrosis models helps clarify how membrane protein misfolding translates into impaired epithelial fluid balance.
Corneal endothelial dysfunction
Corneal endothelial cells rely on transmembrane water and urea transport to maintain corneal deturgescence and transparency. Experimental measurements in rat corneal endothelial cells show that water and urea transport can be quantified, providing a model for diseases involving corneal edema. This links GO:0005372 directly to ocular physiology and potential therapeutic targets.
Glioma proliferation and imaging
In vivo spatiotemporal mapping of proliferation activity in gliomas via water-exchange dynamic contrast-enhanced MRI demonstrates that water transport dynamics correlate with tumor growth. This suggests that water transmembrane transporter activity contributes to imaging biomarkers of proliferation. The approach provides a non-invasive way to study water transport in cancer.
Neuronal activity and brain water cycling
Brain active transmembrane water cycling measured by MR is associated with neuronal activity, linking GO:0005372 to functional neuroimaging. This association implies that water transport is part of the metabolic and physiological response to neuronal firing. Disruptions in this coupling may contribute to neurological conditions, although specific disease mechanisms require further study.
From water transmembrane transporter activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate water transporter reduce membrane water permeability? | CRISPR knockout in epithelial or endothelial cells |
| Does a disease-associated point mutation alter water transport? | Point-mutation knock-in at the endogenous locus |
| Can a tagged water transporter be tracked in live cells? | Knock-in of fluorescent or affinity tag |
| Does overexpression of a water transporter increase water flux? | Overexpression cell model |
| Is water transport coupled to neuronal activity? | In vivo MRI water cycling in animal models |
| Does water-exchange MRI track tumor proliferation? | Orthotopic glioma models with dynamic contrast-enhanced MRI |
How to Study the water transmembrane transporter activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Osmotic swelling assay | Water permeability of cell membranes | Validation of aquaporin activity |
| Stopped-flow light scattering | Rapid water flux kinetics | Quantifying water transport in vesicles or cells |
| Dynamic contrast-enhanced MRI | Water-exchange dynamics in tissue | Mapping tumor proliferation |
| Functional MRI water cycling | Active transmembrane water cycling | Neuronal activity coupling |
| Molecular dynamics simulation | Atomistic water permeation pathways | Mechanistic study of membrane proteins |
| Artificial water channel assays | Engineered water transport | Proof-of-principle for synthetic channels |
| QTY code protein design | Water-soluble receptor kinase function | Engineering water-compatible membrane proteins |
| Urea/water co-transport assay | Coupled solute and water flux | Corneal endothelial transport studies |
Water permeability assays
Water permeability can be measured by osmotic swelling assays and stopped-flow light scattering in cells expressing candidate transporters. These assays quantify the rate of water movement across membranes and are used to validate GO:0005372 annotations. In corneal endothelial cells, water and urea transport have been measured directly, providing a template for epithelial studies.
Magnetic resonance water exchange
Magnetic resonance methods can measure active transmembrane water cycling in living brain tissue and map water-exchange dynamics in tumors. These approaches link molecular water transport to systems-level physiology and imaging biomarkers. They are particularly useful when direct patch-clamp or swelling assays are not feasible in vivo.
Molecular dynamics simulations
Molecular dynamics simulations of membrane proteins such as mitochondrial uncoupling protein 2 reveal water-related transport behavior and conformational states. Simulations complement experimental permeability measurements by providing atomistic insight into water pathways. They can also guide mutagenesis of putative water-permeation residues.
Engineered channel and protein design
Artificial transmembrane water channels and water-soluble receptor kinases demonstrate that water transport and molecular function can be engineered. These systems serve as controls for understanding minimal requirements for water permeation. They also provide platforms for testing design principles relevant to GO:0005372.
How CRISPR Can Be Used to Study GO:0005372 water transmembrane transporter activity
Knockout
CRISPR knockout of candidate water transporter genes, such as AQP1 or AQP4, allows direct testing of whether the gene is required for membrane water permeability in a given cell type. Knockout models are essential for assigning GO:0005372 activity to specific gene products and for distinguishing redundant pathways. In disease contexts, knockout of CFTR in epithelial cells models the loss of function seen in cystic fibrosis.
Point Mutation
Point-mutation knock-in can recreate disease-associated missense mutations that alter water transport or protein trafficking. For example, cystic fibrosis mutations that cause misfolding and misprocessing can be introduced to study their impact on epithelial water balance. Point mutations in water transporter genes can also probe selectivity filters and pore residues.
Knock-in
Knock-in of fluorescent or affinity tags at endogenous loci enables live-cell tracking of water transporters and their localization. Tagged knock-in models are useful for correlating protein abundance with water transport activity. They also facilitate proteomic and imaging studies of membrane protein dynamics.
Overexpression
Overexpression of water transporters or engineered water channels increases water flux and can be used to test sufficiency of GO:0005372 activity. Overexpression models are particularly valuable for artificial channels and designed proteins that lack endogenous regulatory elements. They also help quantify the maximum water transport capacity of a given protein.
How EDITGENE Supports water transmembrane transporter activity Research
Researchers studying water transmembrane transporter activity-related genes often need to determine whether a candidate gene is causally involved in water flux, whether a disease-associated mutation alters transport, and how the protein behaves in a native membrane environment. EDITGENE provides CRISPR-based cell models and screening services to answer these questions with reproducible, publication-ready reagents.
Contact EDITGENE today to design your custom CRISPR model for water transmembrane transporter activity research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| AQP2 Knockout HEK293 Cell Line | EDJ-KQ3141 | Human | 359 | Details Get a Quote |
| SLC5A1 Knockout HEK293 Cell Line | EDJ-KQ5767 | Human | 6523 | Details Get a Quote |
| SLC14A1 Knockout HEK293 Cell Line | EDJ-KQ5790 | Human | 6563 | Details Get a Quote |
| SLC4A11 Knockout HEK293 Cell Line | EDJ-KQ9948 | Human | 83959 | Details Get a Quote |
| SLC4A11 Knockout A-549 Cell Line | EDJ-KQ36853 | Human | 83959 | Details Get a Quote |
| SLC4A11 Knockout HCT 116 Cell Line | EDC08649 | Human | 83959 | Details Get a Quote |
| SLC4A11 Knockout HeLa Cell Line | EDJ-KQ36855 | Human | 83959 | Details Get a Quote |
| AQP1 Knockout HEK293 Cell Line | EDJ-KQ50127 | Human | 358 | Details Get a Quote |
| AQP1 Knockout HeLa Cell Line | EDJ-KQ52644 | Human | 358 | Details Get a Quote |
| AQP2 Knockout HeLa Cell Line | EDJ-KQ52645 | Human | 359 | Details Get a Quote |
| SLC5A1 Knockout HeLa Cell Line | EDJ-KQ54486 | Human | 6523 | Details Get a Quote |
| SLC14A1 Knockout HeLa Cell Line | EDJ-KQ54509 | Human | 6563 | Details Get a Quote |
| AQP1 Knockout A-549 Cell Line | EDJ-KQ61117 | Human | 358 | Details Get a Quote |
| AQP2 Knockout A-549 Cell Line | EDJ-KQ61118 | Human | 359 | Details Get a Quote |
| SLC5A1 Knockout A-549 Cell Line | EDJ-KQ62972 | Human | 6523 | Details Get a Quote |
Displaying Records 1 To 15 Of 20 Records
Frequently Asked Questions About water transmembrane transporter activity
What is GO:0005372 water transmembrane transporter activity?
GO:0005372 is a molecular function term describing the transfer of water (H2O) from one side of a membrane to the other.
What genes are involved in water transmembrane transporter activity?
Aquaporins such as AQP1, AQP2, AQP3, AQP4, and AQP5 are principal genes, and other membrane proteins can also contribute.
How is water transmembrane transport measured?
It is measured by osmotic swelling assays, stopped-flow light scattering, and magnetic resonance water-exchange methods.
Is water transport active or passive?
Water moves down its chemical potential gradient through protein channels, and the process can be dynamically coupled to cellular activity.
What diseases are linked to water transmembrane transporter activity?
Cystic fibrosis, corneal endothelial dysfunction, glioma proliferation, and neuronal activity disorders have been linked.
Can artificial water channels be made?
Yes, single-molecular artificial transmembrane water channels have been synthesized and shown to transport water.
How do CRISPR knockouts help study water transport?
Knockouts remove a candidate gene to test whether it is required for membrane water permeability.
What is the role of AQP4 in the brain?
AQP4 is associated with brain water homeostasis and active transmembrane water cycling linked to neuronal activity.
How does CFTR relate to water transport?
CFTR mutations cause protein misfunction and disturb epithelial ion and water balance, indirectly affecting water transport.
What methods study water transport in tumors?
Dynamic contrast-enhanced MRI water-exchange mapping can track proliferation activity in gliomas.
Conclusion
GO:0005372 water transmembrane transporter activity is a well-defined molecular function that underpins water movement across membranes and is experimentally tractable in cells and living systems. Its relevance spans epithelial physiology, brain function, corneal transparency, and tumor imaging, making it a compelling target for mechanistic and translational research. CRISPR-based models and advanced imaging methods now allow researchers to test causality and regulation of water transport with high precision.
References
- 1. Farinha CM et al.. 2022. Molecular mechanisms of cystic fibrosis - how mutations lead to misfunction and guide therapy.. Biosci Rep 42(7) PMID: 35707985
- 2. Bai R et al.. 2019. Brain active transmembrane water cycling measured by MR is associated with neuronal activity.. Magn Reson Med 81(2):1280-1295 PMID: 30194797
- 3. Škulj S et al.. 2021. Molecular Dynamics Simulations of Mitochondrial Uncoupling Protein 2.. Int J Mol Sci 22(3) PMID: 33530558
- 4. Bai R et al.. 2025. In vivo spatiotemporal mapping of proliferation activity in gliomas via water-exchange dynamic contrast-enhanced MRI.. Theranostics 15(10):4693-4707 PMID: 40225573
- 5. Hu XB et al.. 2012. Single-molecular artificial transmembrane water channels.. J Am Chem Soc 134(20):8384-7 PMID: 22574988
- 6. Li M et al.. 2024. Design of a water-soluble transmembrane receptor kinase with intact molecular function by QTY code.. Nat Commun 15(1):4293 PMID: 38858360
- 7. Adeva-Andany MM et al.. 2017. Significance of l-carnitine for human health.. IUBMB Life 69(8):578-594 PMID: 28653367
- 8. Katkova LE et al.. 2025. Transmembrane Transport of Water and Urea in Rat Corneal Endothelial Cells.. Biochemistry (Mosc) 90(10):1366-1375 PMID: 41176795
