Skip to main content
. 2012 Nov 1;5(11):1177–1209. doi: 10.3390/ph5111177

Figure 1.

Figure 1

Model of the trafficking of a CPP-cargo conjugate through the endocytic pathway. From left to right: A CPP-cargo binds to HSPGs on the cell surface and induces endocytosis. Endocytosis leads to uptake and entrapment of the CPP-cargo inside an endocytic vesicle. The endosomal membrane contains the lipid phosphatidylserine (Ptd-Ser) in its outer leaflet. During endosomal maturation, a vacuolar H+-ATPase acidifies the lumen of endocytic organelles. The CPP-cargo reaches early endosomes (pH~6.5). Concurrently, hydrolases partially degrade HSPGs and release HS fragments. Upon further maturation, the CPP-cargo reaches multivesicular bodies, late endosomes (pH~5.5), and lysosomes (pH~4.5). The membrane of the intraluminal vesicles of late endosomes is enriched with BMP. HS is further degraded to smaller fragments. The CPP-cargo is susceptible to degradation due to the low pH and lysosomal hydrolases.