Class E VPS protein involved in concentration and sorting of cargo proteins of the multivesicular body (MVB) for incorporation into intralumenal vesicles. Fusion between endosomes and the vacuole will then target the cargo proteins to the vacuolar lumen. Acts as an adapter that recruits the DOA4 deubiquitinase to the endosomes, leading to deubiquitination of cargo proteins prior to the lumenal sequestration. Its association to the endosomes depends on SNF7 and its dissociation requires VPS4. Interacts functionally with the Pkc1p-mitogen-activated protein kinase pathway. Interacts with DOA4 and SNF7. The coiled-coil domain is essential for MVB sorting. The BRO1 domain may be involved in the binding to SNF7. Present with 10200 molecules/cell in log phase SD medium.