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Single Extracellular Vesicle Transmembrane Protein Characterization by Nano-Flow Cytometry
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Simultaneous Expression of Sigma-1 Receptor and Tetraspanins Highlights Pathways of Receptor Sorting Into
Edijs Vavers1, Sergei Kopanchuk1, Santa Veiksina1
1University of Tartu, Institute of Chemistry, Tartu, Estonia.
Journal of Neurochemistry
|April 15, 2026
Summary
Sigma-1 receptor (Sig1R) is found in extracellular vesicles (EVs), suggesting a role in neurological disease pathways. This discovery highlights Sig1R
Area of Science:
- Cell Biology
- Neuroscience
- Biochemistry
Background:
- Sigma-1 receptor (Sig1R) is an endoplasmic reticulum chaperone protein linked to neurodegenerative diseases.
- Sig1R's extracellular presence is known, but its presence in extracellular vesicles (EVs) is unconfirmed.
Purpose of the Study:
- To confirm the presence of Sig1R in isolated EVs.
- To investigate Sig1R's association with specific EV markers.
Main Methods:
- Co-expression of fluorescently tagged Sig1R and tetraspanin EV markers (CD9, CD63, CD81) in cells.
- Verification using live-cell imaging, emission spectrum measurements, and Western blotting.
- Detection in EVs via TIRF-based single-particle EV analysis.
Main Results:
- Sig1R was successfully detected in isolated EVs alongside tetraspanin markers.
- Higher Sig1R levels were observed in CD63- and CD9-labeled EVs compared to CD81-labeled EVs.
- Data suggest Sig1R release via exosome secretion pathways.
Conclusions:
- Sig1R is present in exosomes, supporting its potential as a biomarker for neurological disorders.
- Further research is needed to explore Sig1R's diagnostic and therapeutic applications in neurological conditions.
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