The ESCRT (Endosomal Sorting Complexes Required for Transport) machinery is made up of five complexes ESCRT-0 to -III and the Vps4-Vta1 ATPase complex, which are sequentially recruited to the cytosolic face of the membrane, and mediate cargo recognition, membrane budding and fission. ESCRT-I is constitutive heterotetrameric complex. It interacts with ESCRT-O, -II and ubiquitin. Together with ESCRT-II, it mediates the formation of the membrane bud and stabilizes the neck region. (Adapted from PMID:22361144 and FBrf0209668).