FIGURE 1.

Figure of unconventional vs. conventional secretions: Newly synthesized proteins from the ER and exported in COP-II vesicles towards the Golgi apparatus wherein they are packed in secretory vesicles for export via the conventional secretory pathway. Unconventional secretion, in particular the Type III secretion represented here involves packaging of cytosolic proteins as well as the possible targeting of autophagic, ER-derived and mitochondria-derived vesicles to the multivesicular bodies (MVBs) or late endosomes. The resultant intraluminal vesicle can then fuse with the plasma membrane and release exosomes and other mixed content. Autophagosomes and secretory lysosomes can fuse with the plasma membrane directly to release their content in the extracellular space. MVB: Multivesicular body; ILV: Intraluminal vesicle; PM: Plasma membrane. Role of SNAREs and their partners in unconventional secretion.