GO:0015761 mannose transmembrane transport: Transport Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0015761 (mannose transmembrane transport) describes the movement of mannose, the C-2 epimer of glucose, across a lipid bilayer from one side of a membrane to the other.
• Mannose transport is mechanistically linked to lysosomal enzyme trafficking because mannose 6-phosphate receptors (MPRs) deliver acid hydrolases to lysosomes.
• The cation-independent mannose 6-phosphate receptor (IGF2R/CI-MPR) is a multifunctional receptor that also binds IGF-II and is implicated in neurodegenerative disease.
• LYSET (TMEM251) is a Golgi-to-lysosome trafficking factor required for nutritional usage of extracellular proteins, connecting mannose-related trafficking to lysosomal catabolism.
• Golgi-localized monomeric clathrin adaptors (GGAs) and retromer-mediated retrograde transport are key machineries for sorting mannose 6-phosphate receptors.
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable causal dissection of mannose transport genes in lysosomal storage, cancer, and neurodegeneration research.
Description
GO:0015761, mannose transmembrane transport, is a biological process defined as the transport of mannose across a lipid bilayer from one side of a membrane to the other [QuickGO]. Mannose is the aldohexose manno-hexose and the C-2 epimer of glucose; its D-(+)-form is widely distributed in mannans and hemicelluloses and is of major importance in the core oligosaccharide of N-linked oligosaccharides of glycoproteins [QuickGO]. Because mannose is a constituent of N-linked glycans and a precursor for mannose 6-phosphate (M6P) tagging of lysosomal enzymes, its transmembrane movement is central to glycoprotein quality control and lysosomal enzyme delivery. Researchers study GO:0015761 to understand how cells acquire and route mannose for glycosylation, how M6P-dependent sorting is maintained, and how defects in these pathways contribute to lysosomal storage disorders and neurodegeneration. The process intersects with Golgi/endosome sorting machineries, including monomeric clathrin adaptors and retromer-mediated retrograde transport, which determine whether mannose-bearing cargo reaches the correct compartment. In addition, lysosomal nutrient sensing and extracellular protein usage depend on intact mannose-related trafficking, as shown by the requirement for LYSET in lysosomal enzyme transport. Consequently, mannose transmembrane transport is not a standalone event but a hub connecting glycosylation, membrane trafficking, and metabolic signaling.
mannose transmembrane transport At A Glance
| GO ID | GO:0015761 |
|---|---|
| GO term | mannose transmembrane transport |
| Ontology | biological_process |
| Synonym | mannose transport |
| Definition | The process in which mannose is transported across a lipid bilayer, from one side of a membrane to the other. |
| Major function | Delivery of mannose for N-linked glycosylation and mannose 6-phosphate-dependent lysosomal enzyme sorting |
| Related machinery | Mannose 6-phosphate receptors, Golgi clathrin adaptors, retromer-mediated retrograde transport |
| Disease relevance | Lysosomal storage disorders, neurodegeneration, cancer metabolism |
| Key receptor | IGF2R/CI-MPR (cation-independent mannose 6-phosphate receptor) |
What Is GO:0015761?
In our own words, GO:0015761 describes the directed passage of mannose across a cellular membrane. Mannose is an aldohexose sugar that is the C-2 epimer of glucose; its D-(+)-form is abundant in mannans and hemicelluloses and is a key component of the core oligosaccharide of N-linked glycoproteins [QuickGO]. The term encompasses transport from one side of a lipid bilayer to the other, which may occur through dedicated transporters or via vesicular trafficking of mannose-bearing cargo. This process is essential for supplying mannose to glycosylation pathways and for generating mannose 6-phosphate tags that direct lysosomal enzymes.
Why Is mannose transmembrane transport Important in Cell Biology?
Mannose transmembrane transport matters because it supplies a sugar that is both a building block of N-linked glycans and a tag for lysosomal enzyme targeting. The mannose 6-phosphate pathway depends on receptors such as IGF2R/CI-MPR to deliver acid hydrolases to lysosomes, and disruption of this trafficking leads to lysosomal dysfunction. Moreover, the lysosomal enzyme trafficking factor LYSET is required for nutritional usage of extracellular proteins, linking mannose-related transport to cellular catabolism and nutrient sensing. Because Golgi/endosome-localizing clathrin adaptors and retromer-mediated retrograde transport regulate the sorting of these receptors, mannose transport is embedded in the broader membrane trafficking network. Defects in these pathways are associated with neurodegenerative diseases and lysosomal storage disorders, making GO:0015761 a relevant target for mechanistic and therapeutic research.
• Supplies mannose for N-linked glycosylation and glycoprotein biosynthesis.
• Enables mannose 6-phosphate tagging and lysosomal enzyme delivery.
• Connects to IGF2R/CI-MPR, a receptor implicated in neurodegenerative diseases.
• Requires Golgi clathrin adaptors (GGAs) for sorting of mannose 6-phosphate receptors.
• Depends on retromer-mediated retrograde transport for receptor recycling.
• Supports lysosomal nutrient acquisition via LYSET-dependent extracellular protein usage.
• Relevant to lysosomal storage disorders and neurodegeneration.
• Provides a handle for CRISPR screens targeting trafficking and glycosylation genes.
• Links metabolic sugar transport to organelle pH homeostasis.
• Offers biomarkers and therapeutic entry points in cancer and neurodegeneration.
What Happens During mannose transmembrane transport?
Mannose availability and membrane translocation
In simple terms: Mannose must cross a membrane to reach the compartments where it is used.
Mannose is an aldohexose and the C-2 epimer of glucose; its D-(+)-form is widely distributed in mannans and hemicelluloses and is a major component of the core oligosaccharide of N-linked glycoproteins [QuickGO]. The transport step moves mannose across a lipid bilayer from one side of a membrane to the other, supplying the sugar for downstream glycosylation and tagging reactions [QuickGO]. This process is essential for generating mannose 6-phosphate tags that direct lysosomal enzymes.
Mannose 6-phosphate receptor sorting
In simple terms: Receptors grab mannose-tagged enzymes and route them to lysosomes.
Sorting of lysosomal proteins depends on mannose 6-phosphate receptors that recognize M6P tags on acid hydrolases. The cation-independent mannose 6-phosphate receptor (IGF2R/CI-MPR) is a multifunctional receptor involved in neurodegenerative diseases, highlighting the importance of this sorting step. Golgi/endosome-localizing monomeric clathrin adaptors (GGAs) participate in the recognition and packaging of these receptors.
Vesicular trafficking and retrograde transport
In simple terms: Vesicles carry receptors back and forth so they can be reused.
Retromer-mediated retrograde transport is facilitated by gamma-secretase and is required for recycling of mannose 6-phosphate receptors. This retrieval pathway maintains the steady-state distribution of receptors between Golgi and endosomes, which is necessary for continuous lysosomal enzyme delivery. Disruption of this trafficking impairs lysosomal function and nutrient usage.
Lysosomal nutrient usage and pH regulation
In simple terms: Once cargo arrives, lysosomes digest it and maintain an acidic environment.
LYSET (TMEM251) is a lysosomal enzyme trafficking factor that enables nutritional usage of extracellular proteins, linking mannose-related trafficking to lysosomal catabolism. Lysosomal pH is tightly regulated, and genetically encoded biosensors have been used to image intra-lysosome pH in cell lines and primary neuronal culture. Proper pH is required for the activity of mannose 6-phosphate receptor-dependent hydrolases.
Conformational quality control in the secretory pathway
In simple terms: Proteins must fold correctly or they are degraded.
Conformational disease mechanisms arise when proteins misfold, and quality control in the secretory pathway determines whether they are rescued or degraded. Mannose trimming and N-linked glycan processing are part of this quality control, and mannose transmembrane transport supplies the substrate for these reactions [QuickGO]. Defects in this axis can contribute to protein aggregation and neurodegeneration.
Key Genes Involved in GO:0015761 mannose transmembrane transport
The following genes and proteins are mechanistically linked to mannose transmembrane transport, mannose 6-phosphate receptor trafficking, and lysosomal enzyme sorting.
| Gene | Major Role | Research Relevance |
|---|---|---|
| IGF2R (CI-MPR) | Cation-independent mannose 6-phosphate receptor that binds M6P-tagged lysosomal enzymes and IGF-II | Implicated in neurodegenerative diseases; key receptor for lysosomal enzyme delivery |
| LYSET (TMEM251) | Lysosomal enzyme trafficking factor enabling nutritional usage of extracellular proteins | Required for lysosomal catabolism and mannose-related trafficking |
| GGA1 | Golgi-localized monomeric clathrin adaptor involved in sorting of mannose 6-phosphate receptors | Regulates receptor packaging at the TGN |
| GGA2 | Golgi-localized monomeric clathrin adaptor involved in sorting of mannose 6-phosphate receptors | Regulates receptor packaging at the TGN |
| GGA3 | Golgi-localized monomeric clathrin adaptor involved in sorting of mannose 6-phosphate receptors | Regulates receptor packaging at the TGN |
| VPS35 | Retromer component mediating retrograde transport of cargo receptors | Required for recycling of mannose 6-phosphate receptors |
| VPS26 | Retromer component mediating retrograde transport of cargo receptors | Required for recycling of mannose 6-phosphate receptors |
| VPS29 | Retromer component mediating retrograde transport of cargo receptors | Required for recycling of mannose 6-phosphate receptors |
| PSEN1 | Gamma-secretase subunit that facilitates retromer-mediated retrograde transport | Modulates receptor recycling |
| PSEN2 | Gamma-secretase subunit that facilitates retromer-mediated retrograde transport | Modulates receptor recycling |
| NCSTN | Gamma-secretase subunit that facilitates retromer-mediated retrograde transport | Modulates receptor recycling |
| APH1 | Gamma-secretase subunit that facilitates retromer-mediated retrograde transport | Modulates receptor recycling |
| PEN2 | Gamma-secretase subunit that facilitates retromer-mediated retrograde transport | Modulates receptor recycling |
| CLTC | Clathrin heavy chain involved in vesicle formation at the TGN and endosomes | Supports GGA-dependent sorting |
| CLTA | Clathrin light chain involved in vesicle formation | Supports GGA-dependent sorting |
| ATP6V1A | V-ATPase subunit regulating lysosomal pH | Required for lysosomal hydrolase activity |
| ATP6V0A1 | V-ATPase subunit regulating lysosomal pH | Required for lysosomal hydrolase activity |
How Is mannose transmembrane transport Regulated?
Mannose transmembrane transport and its downstream sorting steps are regulated at multiple levels. Golgi-localized monomeric clathrin adaptors (GGAs) control the packaging of mannose 6-phosphate receptors at the trans-Golgi network, and their activity determines the efficiency of lysosomal enzyme delivery. Retromer-mediated retrograde transport, facilitated by gamma-secretase, regulates the recycling of these receptors and thus the steady-state distribution of the sorting machinery. Lysosomal pH, maintained by the V-ATPase, is a critical parameter that can be monitored with genetically encoded biosensors and influences hydrolase activity. In addition, LYSET-dependent trafficking is required for nutritional usage of extracellular proteins, coupling mannose-related transport to nutrient availability. Conformational quality control in the secretory pathway further modulates whether mannose-bearing glycoproteins are rescued or degraded.
mannose transmembrane transport and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| IGF2R (CI-MPR) | Neurodegenerative diseases; IGF-II signaling | Knockout and point-mutation models in neuronal cell lines |
| LYSET (TMEM251) | Lysosomal nutrient usage; lysosomal storage | Knockout in HeLa or HEK293 cells followed by proteomics |
| GGA1/2/3 | Mannose 6-phosphate receptor sorting defects | Knockout and tagged knock-in in HeLa cells |
| VPS35 | Retromer dysfunction; neurodegeneration | Knockout and point-mutation in neuronal cultures |
| ATP6V1A | Lysosomal pH dysregulation | Knockout with pH biosensor imaging |
Neurodegeneration and mannose 6-phosphate receptor dysfunction
The cation-independent mannose 6-phosphate receptor (IGF2R/CI-MPR) is a multifunctional receptor that binds both M6P-tagged lysosomal enzymes and IGF-II, and it has been implicated in neurodegenerative diseases. Disrupted sorting of lysosomal enzymes can lead to impaired lysosomal degradation and accumulation of toxic proteins, a hallmark of conformational disease. Retromer-mediated retrograde transport, which recycles these receptors, is facilitated by gamma-secretase, and its dysfunction is linked to neurodegeneration. These observations place mannose transmembrane transport and its associated trafficking machinery at the center of neurodegenerative disease mechanisms.
Lysosomal storage disorders and nutrient usage
Lysosomal enzyme trafficking factor LYSET (TMEM251) is required for nutritional usage of extracellular proteins, and its loss impairs lysosomal catabolism. Mannose 6-phosphate receptor-dependent sorting is essential for delivering acid hydrolases to lysosomes, and defects in this pathway cause lysosomal storage disorders. Lysosomal pH regulation, monitored with genetically encoded biosensors, is also critical for hydrolase activity and is perturbed in lysosomal dysfunction. Together, these findings link mannose transmembrane transport to lysosomal storage disease biology.
Cancer metabolism and glycosylation
Mannose is a component of N-linked glycans, and altered glycosylation is a hallmark of cancer metabolism [QuickGO]. Because mannose transmembrane transport supplies substrate for glycosylation, changes in this process can affect cell surface glycoproteins and signaling. The IGF2R/CI-MPR also binds IGF-II, a growth factor implicated in cancer and neurodegeneration, connecting mannose-related trafficking to growth signaling. Targeting these pathways with CRISPR models may reveal vulnerabilities in cancer cells dependent on glycosylation and lysosomal function.
From mannose transmembrane transport-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is a candidate gene required for mannose 6-phosphate receptor trafficking? | CRISPR knockout in HeLa or HEK293 cells |
| Does a disease-associated point mutation alter receptor recycling? | Point-mutation knock-in in neuronal cell lines |
| Can a tagged receptor be tracked in live cells? | Tagged knock-in of IGF2R with fluorescent protein |
| Does overexpression of LYSET rescue lysosomal enzyme trafficking? | Overexpression in LYSET-knockout cells |
| Does loss of retromer components alter lysosomal pH? | Knockout with genetically encoded pH biosensor |
| Can glycosylation changes be detected after mannose transport perturbation? | Knockout plus lectin-based proteomics |
How to Study the mannose transmembrane transport Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell pH biosensor imaging | Intra-lysosome pH | Assessing lysosomal function after knockout |
| Proteomics of lysosomal fractions | Cargo content and enzyme delivery | Mapping LYSET-dependent trafficking |
| Fluorescence microscopy of tagged receptors | Receptor localization and recycling | Testing retromer and gamma-secretase mutants |
| Lectin-based glycan profiling | N-linked glycosylation status | Evaluating mannose supply to glycoproteins |
| CRISPR knockout screening | Gene requirement for trafficking | Identifying novel mannose transport regulators |
| Western blot of M6P-tagged enzymes | Maturation and sorting of hydrolases | Validating GGA and retromer function |
| Neuronal culture imaging | pH and trafficking in primary neurons | Modeling neurodegenerative disease |
Live-cell imaging of lysosomal pH
Genetically encoded biosensors enable live imaging of intra-lysosome pH in cell lines and primary neuronal culture, providing a functional readout for mannose 6-phosphate receptor-dependent trafficking. This method can be combined with CRISPR knockout of trafficking genes to determine how mannose transport affects lysosomal acidity.
Proteomics of lysosomal enzyme trafficking
Proteomic analysis of lysosomal fractions after LYSET knockout reveals defects in nutritional usage of extracellular proteins and identifies cargo dependent on mannose-related trafficking. Such workflows can be applied to GGA and retromer mutants to map the sorting network.
Fluorescence imaging of receptor recycling
Tagged knock-in of mannose 6-phosphate receptors allows tracking of retrograde transport and recycling in live cells. This approach is useful for testing point mutations in retromer or gamma-secretase components.
Glycosylation profiling
Lectin-based and mass spectrometry-based glycan profiling can measure changes in N-linked glycosylation after perturbation of mannose transmembrane transport. These methods connect mannose supply to glycoprotein quality control and conformational disease mechanisms.
How CRISPR Can Be Used to Study GO:0015761 mannose transmembrane transport
Knockout
CRISPR knockout of genes such as LYSET, GGA1/2/3, or VPS35 enables loss-of-function studies of mannose transmembrane transport and receptor sorting. Knockout cells can be analyzed by proteomics, pH imaging, and glycosylation profiling to define the requirement for each factor.
Point Mutation
Point-mutation knock-in models can mimic disease-associated variants in IGF2R, VPS35, or gamma-secretase subunits to test effects on receptor recycling and lysosomal function. These models are valuable for distinguishing pathogenic from benign variants in neurodegeneration research.
Knock-in
Tagged knock-in of mannose 6-phosphate receptors or trafficking factors allows live-cell tracking of retrograde transport and recycling. Knock-in of fluorescent or affinity tags preserves endogenous regulation and enables imaging and proteomic workflows.
Overexpression
Overexpression of LYSET or receptor components can rescue trafficking defects in knockout backgrounds and test sufficiency of a candidate gene. Overexpression models are also useful for structure-function studies of mannose 6-phosphate receptor domains.
How EDITGENE Supports mannose transmembrane transport Research
Researchers studying mannose transmembrane transport-related genes often need to determine whether a candidate gene is causally involved in receptor sorting, lysosomal enzyme delivery, or glycosylation. EDITGENE provides publication-ready CRISPR cell models and screening services to test these hypotheses with rigor and reproducibility.
Contact EDITGENE today to design your custom CRISPR model for mannose transmembrane transport research.
Frequently Asked Questions About mannose transmembrane transport
What is mannose transmembrane transport?
Mannose transmembrane transport (GO:0015761) is the process in which mannose is transported across a lipid bilayer from one side of a membrane to the other [QuickGO].
What genes are involved in mannose transmembrane transport?
Key genes include IGF2R (CI-MPR), LYSET (TMEM251), GGA1/2/3, VPS35, and gamma-secretase subunits such as PSEN1.
Why is mannose transmembrane transport important for lysosomes?
It supplies mannose for mannose 6-phosphate tagging, which is required for sorting acid hydrolases to lysosomes via receptors such as IGF2R/CI-MPR.
How is mannose 6-phosphate receptor trafficking regulated?
Golgi-localized clathrin adaptors (GGAs) and retromer-mediated retrograde transport regulate receptor packaging and recycling.
What diseases are linked to mannose transmembrane transport?
Neurodegenerative diseases, lysosomal storage disorders, and cancer metabolism have been linked to this pathway.
What is the role of LYSET in mannose transport?
LYSET (TMEM251) is a lysosomal enzyme trafficking factor required for nutritional usage of extracellular proteins.
How can I study mannose transmembrane transport in the lab?
CRISPR knockout, point-mutation knock-in, tagged knock-in, and overexpression models combined with pH imaging and proteomics are standard approaches.
What is the cation-independent mannose 6-phosphate receptor?
IGF2R/CI-MPR is a multifunctional receptor that binds M6P-tagged lysosomal enzymes and IGF-II and is implicated in neurodegenerative diseases.
Does gamma-secretase regulate mannose 6-phosphate receptor recycling?
Yes, gamma-secretase facilitates retromer-mediated retrograde transport, which recycles mannose 6-phosphate receptors.
What methods measure lysosomal pH in mannose transport studies?
Genetically encoded biosensors enable live imaging of intra-lysosome pH in cell lines and primary neuronal culture.
Conclusion
GO:0015761 mannose transmembrane transport is a fundamental biological process that supplies mannose for N-linked glycosylation and mannose 6-phosphate-dependent lysosomal enzyme sorting. Its machinery intersects with Golgi clathrin adaptors, retromer-mediated retrograde transport, and lysosomal pH regulation, and its dysfunction is linked to neurodegeneration and lysosomal storage disorders. CRISPR-based knockout, point-mutation, knock-in, and overexpression models provide powerful tools to dissect these mechanisms and identify therapeutic targets. EDITGENE supports this research with publication-ready cell models and screening services tailored to mannose transport and trafficking biology.
References
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- 3. Uemura T et al.. 2020. Emerging roles of Golgi/endosome-localizing monomeric clathrin adaptors GGAs.. Anat Sci Int 95(1):12-21 PMID: 31659673
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- 5. Takeo Y et al.. 2024. γ-secretase facilitates retromer-mediated retrograde transport.. bioRxiv PMID: 38895404
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- 7. Takeo Y et al.. 2025. γ-secretase facilitates retromer-mediated retrograde transport.. J Cell Sci 138(4) PMID: 39865938
- 8. Wang Y et al.. 2017. Insulin-Like Growth Factor-II/Cation-Independent Mannose 6-Phosphate Receptor in Neurodegenerative Diseases.. Mol Neurobiol 54(4):2636-2658 PMID: 26993302
