This family of conserved eukaryotic proteins are subunits of the endosome associated complex ESCRT-II which recruits transport machinery for protein sorting at the multivesicular body (MVB) [1]. This protein complex transiently associates with the endosomal membrane and thereby initiates the formation of ESCRT-III, a membrane-associated protein complex that functions immediately downstream of ESCRT-II during sorting of MVB cargo. ESCRT-II in turn functions downstream of ESCRT-I, a protein complex that binds to ubiquitinated endosomal cargo [1].

1: Endosome-associated complex, ESCRT-II, recruits transport machinery for protein sorting at the multivesicular body. Babst M, Katzmann DJ, Snyder WB, Wendland B, Emr SD; Dev Cell 2002;3:283-289. PMID:12194858

2: ESCRT-II, an endosome-associated complex required for protein sorting: crystal structure and interactions with ESCRT-III and membranes. Teo H, Perisic O, Gonzalez B, Williams RL; Dev Cell 2004;7:559-569. PMID:15469844