FIGURE 7:

A model for ESCRT-II–mediated coupling of ILV formation with cargo sorting. The early ESCRT complexes (ESCRT-0 and ESCRT-I) concentrate transmembrane cargo along with lipids interacting with the cargoes. The resulting cargo–ESCRT–lipid patch deforms the endosomal membrane. Subsequent recruitment and activation of ESCRT-II causes ESCRT-III polymerization. Vps4-mediated constriction of ESCRT-III results in deepening of the membrane invagination and ultimately fission of the ILV neck. In the absence of ESCRT-0 and ESCRT-I, ESCRT-II(S) randomly initiates ESCRT-III polymerization. However, in the absence of a cargo patch, Vps4-mediated remodeling of ESCRT-III does not result in ILV formation.