Class E VPS protein implicated in concentration and sorting of cargo proteins of the multivesicular body (MVB) for incorporation into intralumenal vesicles. The lumenal sequestrated membrane proteins will be targeted into the vacuole after fusion of the endosome with the vacuole. Acts a component of the ESCRT-III complex, which appears to be critical for late steps in MVB sorting, such as membrane invagination and final cargo sorting and recruitment of late-acting components of the sorting machinery. The MVB pathway requires the sequential function of ESCRT-O, -I,-II and -III complex assemblies. Required for the oligomerization of SNF7 into a membrane-associated filament. The VPS20-SNF7 subcomplex is responsible for the membrane association of the ESCRT-III complex. Also required for the RIM101 repressor proteolytic activation.