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Exosomes biogenesis
Exosome formation starts with the invagination of the the multi-vesicular bodies (MVBs) or late endosomes to generate intraluminal vesicles (ILVs). There are various proposed mechanisms for formation of MVBs, vesicle budding, and sorting. The most studies and well known is the endosomal sorting complex required for transport (ESCRT )dependent pathway. ESCRT machinery mediates the ubiquitinated pathway consisting of protein complexes; ESCRT-0, -I, -II, -III, and the associated ATPase Vps4. ESCRT 0 recognizes and retains ubiquitinated proteins marked for packaging in the late endosomal membrane. ESCRT I/II recognizes the ESCRT 0 and starts creating involution of the membrane into the MVB. ESCRTIII forms a spiral shaped structure constricting the neck. ATPase VPS4 protein drives the membrane scission. Syndecan-syntenin-ALIX exosome biogenesis pathway are one of the ESCRT-independent or non-canonical pathways for exosome biogenesis.

Exosome secretion
The MVBs once formed are trafficked to the internal side of the plasma membrane. These MVBs are transported to the plasma membrane leading to fusion. Many studies have shown that MVBs having higher cholesterol content fuse with the plasma membrane thus releasing exosomes .The Rab proteins especially Rab 7 attached to the MVB recognizes its effector receptor. The SNARE complex (soluble N- ethylmaleimide- sensitive fusion attachment protein receptor) from the MVB and the plasma membrane interacts and mediates fusion.

Exosome uptake
One of the most prime interest in exosome research is due to the specificity of targeting by exosomes. The exact mechanisms is yet limited with docking of the exosomes with specific protein, sugar, or lipid interactions, or through micro (or micropinocytosis). The internalized exosomes are targeted to the endosomes which release their content in the recipient cell

Sorting and packaging of cargoes in exosomes
Exosomes contain different cargoes; proteins, lipids, and nucleic acids. These cargoes are specifically sorted and packaged into exosomes. The contents packaged into exosomes are cell type specific and also influenced by cellular conditions. Exosomal microRNAs (exomiRs) and proteins are sorted and packaged in exosomes. Villarroya-Beltri and colleagues identified a conserved GGAG specific motif, EXOmotif, in the miRNA packaged in the exosomes which was absent in the cytosolic miRNA (CLmiRNA), which binds to sumoylated heterogeneous nuclear riboprotein (hnRNP) A2B1 for exosome specific miRNA packaging. Proteins are packaged in ESCRT, tertraspanins, lipid- dependent mechanisms. Exosomes are enriched in cholesterol, spingomyelin, saturated phosphatidylcholine and phosphatyletanolamine as compared to the plasma membrane of the cell.