Probable core component of the endosomal sorting required for transport complex III (ESCRT-III) which is involved in multivesicular bodies (MVBs) formation and sorting of endosomal cargo proteins into MVBs. MVBs contain intraluminal vesicles (ILVs) that are generated by invagination and scission from the limiting membrane of the endosome and mostly are delivered to lysosomes enabling degradation of membrane proteins, such as stimulated growth factor receptors, lysosomal enzymes and lipids. The MVB pathway appears to require the sequential function of ESCRT-O, -I,-II and -III complexes. ESCRT-III proteins mostly dissociate from the invaginating membrane before the ILV is released. The ESCRT machinery also functions in topologically equivalent membrane fission events, such as the terminal stages of cytokinesis. Together with SPAST, the ESCRT-III complex promotes nuclear envelope sealing and mitotic spindle disassembly during late anaphase. Recruited to the reforming nuclear envelope (NE) during anaphase by LEMD2 (By similarity). ESCRT-III proteins are believed to mediate the necessary vesicle extrusion and/or membrane fission activities, possibly in conjunction with the AAA ATPase VPS4. Probable core component of the endosomal sorting required for transport complex III (ESCRT-III). ESCRT-III components are thought to multimerize to form a flat lattice on the perimeter membrane of the endosome. Several assembly forms of ESCRT-III may exist that interact and act sequentially. In vitro, heteromerizes with CHMP3 (but not CHMP4) to form helical tubular structures that expose membrane-interacting sites on the outside whereas VPS4B can associate on the inside of the tubule. Interacts with CHMP1B, CHMP2B, CHMP3, CHMP4A, CHMP4B, CHMP4C and CHMP5. Interacts with VPS4A; the interaction is direct. Interacts with VPS4B; the interaction is direct. Interacts with MITD1. Interacts with VTA1; the interaction probably involves the open conformation of CHMP2A (By similarity). Localizes to the midbody of dividing cells. Localized in two distinct rings on either side of the Fleming body. Localizes to the reforming nuclear envelope on chromatin disks during late anaphase (By similarity). Widely expressed. Highly expressed in brain, heart, liver and kidney. The acidic C-terminus and the basic N-termminus are thought to render the protein in a closed, soluble and inactive conformation through an autoinhibitory intramolecular interaction. The open and active conformation, which enables membrane binding and oligomerization, is achieved by interaction with other cellular binding partners, probably including other ESCRT components. ISGylated in a CHMP5-dependent manner. Isgylation weakens and inhibits its interactions with VPS4A and VTA1 respectively (By similarity). Belongs to the SNF7 family.