Figure 2.

Active protein sorting into Intraluminal vesicles. During the intraluminal vesicles formation in the endosomes, proteins are sorted by the heparanase-syntenin-ALIX-ESCRT mechanism. Syndecans with long heparan sulfate chains are trimmed by heparanase and clustered after proteolytic cleavage. Syntenin couples to endosomal sorting complexes required for transport (ESCRT) machinery via Alix protein, then recruits the clustered syndecans with associated proteins and growth factors. Proteins associated with tetraspanin-enriched microdomains are probably inserted in ILVs via CD63, which is also recruited by syntenin [49].