Figure 1

Composition of exosomes. Exosomes and microvesicles are membrane-bound extracellular vesicles secreted from various cell types. Exosomes are 30 to 100 nm in size and packed with a variety of cellular components including mRNAs, miRNAs and proteins that are often selectively packaged from the cell the vesicles are shed. The exosome membrane is decorated with various proteins involved in antigen presentation called major histocompatibility complexes (MHC I and II), targeting and adhesion (integrins and tetraspanins), membrane trafficking (annexins and Rab proteins) as well as lipid-rafts.