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. Author manuscript; available in PMC: 2024 Apr 25.
Published in final edited form as: Immunol Rev. 2022 Jul 8;312(1):76–102. doi: 10.1111/imr.13107

FIGURE 1.

FIGURE 1

Biogenesis and secretion of exosomes and microvesicles. Microvesicles are generated by outward budding of the plasma membrane with the help of several GTPases. The process of biogenesis and release of exosomes into the extracellular space encompasses several distinct steps: (1) invagination of plasma membrane and formation of early endosomes, (2) inward protrusion of early endosomal membrane to generate late endosomes, (3) formation of multivesicular bodies (MVBs) that contain intraluminal vesicles (ILVs), (4) docking of the MVBs to the cellular plasma membrane, (5) exocytosis of the exosomes into the extracellular milieu. Some of the MVBs may go into lysosomal degradation. Several molecules are involved in the biogenesis and release of microvesicles and exosomes. ESCRT, endosome sorting complex required for transport; RAB, RAS-related protein; ALIX, ALG-2 interacting protein X; nSMase2, neutral sphingomyelinase 2; SNARE, soluble NSF attachment protein receptor; VAMP7, vesicle-associated membrane protein 7; SNAP23, synaptosomal-associated protein 23; Syx1A, syntaxin 1A; ARF, ADP, ribosylation factor; RohA, Ras homolog family member A; A-SMase, acid sphingomyelinase