Table 1.
Biochemical profile of exosomes.
| Type of biomolecule | Name of the biomolecule | Host cell function | Exosomal function | Reference |
|---|---|---|---|---|
| Protein | Tetraspanins (CD81, CD82, CD37, CD63) | Organization of the membrane and intracellular protein in to microdomain of intercellular adhesion, signaling and adaptor and | Trafficking of other proteins (MHC class II, ICAM-1, SDC1-4, Ig family) through exosomes Inclusion of integrins by tetraspanins, play important role in precancerous lesion development |
[47,48] |
| Viral membrane proteins (Envelop proteins) | Viral replication in the infected host cells | Virus utilizes exosome biogenesis for viral assembly and transmission Influence exosomal function in immunosuppression |
[49,50] | |
| Immunosuppressive proteins (PD-L1 & CD 100) | Immunosuppression by interacting with immune cells | Reprogramming the immune system far from tumor site | [51,52] | |
| Integral membrane signaling proteins/growth factor receptors (EGFR, SDFR, VEGFR, Cytokine receptors, T cell receptors, GCPR, Notch receptors) | Phosphorylation of tyrosine residues from various intracellular signaling molecules | Surface signaling in the recipient cells and delivery of functional receptors to cells where the specific proteins were downregulated | [53,54] | |
| Lipid-anchored proteins (GPI-anchored proteins, ectonucleotidases, complement inhibiting proteins, cellular prion proteins, glypican-1, prenylated, myristoylated, palmitoylated proteins) | Adhesion, hydrolysis, complement regulation, embryogenesis, apoptosis, neurotransmission, cellular growth and differentiation | Key roles in cancer progression | [[55], [56], [57], [58]] | |
| Enzymes (CD39, CD73, phosphatases, pyrophosphatases, annexins, phosphate transporters, RNA editing enzymes) | Catalysis of physiologically important reaction at intracellular and systemic level | Energy metabolism | ||
| Peripheral Surface Proteins (Wnt proteins, bone morphogenic proetiens, TGF-β, TNF-α. FAS ligand, TRAIL, extracellular matrix proteins-Fibronectin, tenascin C, etc.) | Cell growth and development, apoptosis, Bone formation, morphogenic signals, immunomodulation, extracellular matrix formation and cell integrity | Surface signaling and delivery to the recipient cells | ||
| Lipids and derivatives | Phospholipids | Intracellular signaling, cellular integrity and protection | Exosomal membrane structure | [[59], [60], [61], [62]] |
| Ceramides | Induction of apoptosis, skin hydrophobicity and protection, hormonal function in insulin related pathway | |||
| Glycosphingolipids/gangliosides | Neurological function and cell membrane of the CNS | |||
| Cholesterol | Membrane structure, intracellular signaling, precursors for steroid hormones | |||
| Carbohydrates and derivatives | Sialic acids | Intercellular interactions, carbohydrate-protein interaction, tumor metastasis, bacterial/viral inhibition | Tumor progression | [63] |
| Hyaluron sulphate | Wound healing, carbohydrate-protein interaction, tumor progression | [64,65] | ||
| Heparan sulphate | Wound healing, host defense, energy metabolism, morphogenesis | [66] | ||
| Nucleic acids | RNA (Oct-4 mRNA, ncRNA, snRNA, tRNA, miRNA) | Regulation gene expression for cellular signaling | RNA quality control, Cellular signaling in progression of glioblastoma cells and mast cells | [[67], [68], [69]] |
| DNA (dsDNA, ssDNA, mitochondrial DNA) | Gene expression | DNA quality control, chemoresistance of cancer cells, viral infection | [70,71] |