1. Introduction to CD63

CD63, also known as Cluster of Differentiation 63, is a member of the tetraspanin protein family. It is a highly glycosylated membrane protein involved in several cellular processes, including intracellular trafficking, membrane organization, vesicle formation, and cell signaling.

CD63 is predominantly localized in late endosomes, lysosomes, and multivesicular endosomes, although it can also be detected at the plasma membrane. Its distribution makes it an important protein for investigating intracellular membrane dynamics and extracellular vesicle biology.

2. Molecular Structure and Characteristics of CD63

CD63 belongs to the transmembrane-4 superfamily (TM4SF), commonly referred to as the tetraspanin family. Its molecular structure contains four transmembrane domains, two extracellular loops, and intracellular N- and C-terminal regions.

The characteristic structural features of CD63 include:

• Four transmembrane alpha-helical domains.
• A small extracellular loop and a larger extracellular loop.
• Extensive glycosylation of the large extracellular loop.
• Intracellular targeting signals involved in protein trafficking.
• Interactions with other membrane proteins within tetraspanin-enriched microdomains.

These structural characteristics contribute to CD63 localization and its interactions with proteins involved in membrane organization and intracellular transport.

3. CD63 and Extracellular Vesicles

One of the most widely studied functions of CD63 is its association with extracellular vesicles (EVs), particularly small extracellular vesicles commonly referred to as exosomes.

Exosomes originate from the endosomal pathway. During their formation, intraluminal vesicles accumulate inside multivesicular endosomes. These compartments can subsequently fuse with the plasma membrane, releasing vesicles into the extracellular environment.

CD63 is frequently detected in these vesicles and is widely used as one of the molecular markers for extracellular vesicle characterization.

4. Biological Functions of CD63

Beyond its association with extracellular vesicles, CD63 participates in multiple cellular processes.

Intracellular trafficking

CD63 contributes to the transport and distribution of membrane-associated proteins between intracellular compartments. Its localization in late endosomes and lysosomes is closely linked to membrane trafficking pathways.

Membrane organization

As a tetraspanin, CD63 participates in protein interactions and the organization of specialized membrane microdomains. These interactions can influence the localization and trafficking of associated proteins.

Cellular communication

Through its association with extracellular vesicles, CD63 is relevant to studies investigating intercellular communication and the transfer of biological molecules between cells.

Lipid and cholesterol transport

Research published in Nature Cell Biology in 2024 demonstrated that CD63 participates in cholesterol sorting within endosomal compartments and its distribution through exosomes.

5. Research Applications of CD63 Detection

Detection of CD63 is an important component of many experimental approaches in cell biology and extracellular vesicle research.

• Western Blot: Detection of CD63 protein expression in cell lysates and extracellular vesicle preparations.
• Immunofluorescence: Investigation of CD63 localization and intracellular distribution.
• Immunohistochemistry: Examination of CD63 expression in tissue samples, depending on antibody validation.
• Flow Cytometry: Analysis of CD63 expression on cells or appropriately prepared extracellular vesicles.
• Immunoaffinity-based isolation: Use of CD63-targeting antibodies in approaches designed to capture CD63-positive extracellular vesicles.

Experimental conditions, sample preparation, antibody specificity, and validation are important factors when selecting a detection method.

6. Anti-CD63 Antibodies in Research

Anti-CD63 antibodies are useful molecular tools for investigating CD63 expression, localization, and biological functions. By specifically recognizing CD63, these antibodies can support research workflows involving protein detection and extracellular vesicle characterization.

The choice of antibody depends on the intended application, sample type, species reactivity, epitope accessibility, and experimental validation. Researchers should consult the product documentation to confirm application-specific suitability.

RESEARCH TOOL

Anti-CD63 Antibody

This Anti-CD63 antibody is a research reagent intended for studies involving the CD63 protein. It can be considered for experimental workflows investigating CD63 expression and its biological role in membrane trafficking and extracellular vesicle research, subject to application-specific validation.

Product	Anti-CD63 antibody
Catalog Number	0820-PAab01490
Size	100 µg
Dry Ice	No
Hazardous	No
Shipping Conditions	2–8°C
Storage	According to the label

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24/48H Stock Items & 2 to 6 Weeks non Stock Items.

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7. Future Perspectives in CD63 Research

Ongoing research continues to investigate the role of CD63 in extracellular vesicle biogenesis, intracellular transport, lipid distribution, and cellular communication.

Improved understanding of CD63-positive vesicle populations may contribute to the development of more refined extracellular vesicle isolation and characterization strategies. These investigations are also relevant to biomarker discovery and studies of disease-associated cellular changes.

Scientific References

1. Pols MS, Klumperman J. Trafficking and function of the tetraspanin CD63. Experimental Cell Research. 2009;315(9):1584–1592. https://doi.org/10.1016/j.yexcr.2008.09.020
2. Kaur S, et al. CD63, MHC class 1, and CD47 identify subsets of extracellular vesicles containing distinct populations of noncoding RNAs. Scientific Reports. 2018;8:2577. https://doi.org/10.1038/s41598-018-20936-7
3. Tognoli ML, et al. Lack of involvement of CD63 and CD9 tetraspanins in the extracellular vesicle content delivery process. Communications Biology. 2023;6:532. https://doi.org/10.1038/s42003-023-04911-1
4. Palmulli R, et al. CD63 sorts cholesterol into endosomes for storage and distribution via exosomes. Nature Cell Biology. 2024;26:1093–1109. https://doi.org/10.1038/s41556-024-01432-9
5. Duke LC, et al. Tetraspanin CD9 alters cellular trafficking and endocytosis of tetraspanin CD63, affecting CD63 packaging into small extracellular vesicles. Journal of Biological Chemistry. 2025;301(3):108255. https://doi.org/10.1016/j.jbc.2025.108255