Acts a component of the ESCRT-III complex required for the sorting and concentration of proteins resulting in the entry of these proteins into the invaginating vesicles of the multivesicular body (MVB) (PubMed:11559748, PubMed:12194857). The sequential action of ESCRT-0, -I, and -II together with the ordered assembly of ESCRT-III links membrane invagination to cargo sorting (PubMed:12194857). Membrane scission in the neck of the growing vesicle releases mature, cargo-laden ILVs into the lumen (PubMed:24139821, PubMed:24711499). ESCRT-III is 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 (PubMed:24139821, PubMed:24711499). SNF7 is the most abundant ESCRT-III subunit which forms membrane-sculpting filaments with 30 Angstrom periodicity and a exposed cationic membrane-binding surface (PubMed:26670543). Its activation requires a prominent conformational rearrangement to expose protein-membrane and protein-protein interfaces (PubMed:26670543). SNF7 filaments then form spirals that could function as spiral springs (PubMed:26522593). The elastic expansion of compressed SNF7 spirals generates an area difference between the two sides of the membrane and thus curvature which could be the origin of membrane deformation leading eventually to fission (PubMed:26522593). SNF7 recruits BRO1, which in turn recruits DOA4, which deubiquitinates cargos before their enclosure within MVB vesicles (PubMed:11029042, PubMed:15935782). ESCRT-III is also recruited to the nuclear envelope (NE) by integral INM proteins to surveil and clear defective nuclear pore complex (NPC) assembly intermediates to ensure the fidelity of NPC assembly (PubMed:25303532).