Figure 4.

Mammalian endosomal microautophagy. Left, cytosolic proteins can be sequestered along with other cytosolic components by the invaginations that form in the surface of the endosomal membrane through the coordinated function of ESCRT (VPS4A/B and TSG101) and accessory proteins (Alix). Right, selective targeting to late endosomes of proteins bearing a KFERQ-like motif is mediated by hsc70. Upon cargo binding, hsc70 interacts directly with phosphatidylserine (PS) moieties of the endosomal membrane and is internalized along with the substrate in ESCRT-mediated microvesicles. Part of the internalized vesicles undergoes degradation in the endosomal lumen.