Involved in ESCRT-dependent multivesicular body (MVB) formation and sorting of endosomal cargo proteins into MVBs. Mediates the MVB sorting of the auxin carriers PIN1, PIN2 and AUX1. Required for embryonic axis establishment and seedling growth (PubMed:19304934). Required for autophagic degradation of plastid proteins. Promotes the efficient sequestration of cargo from plastids into autophagosomes. Mediates the efficient delivery of autophagic plastid bodies to the vacuole, but not into the cytoplasm (PubMed:25649438). Interacts with SKD1/VPS4 and LIP5 (PubMed:19304934, PubMed:20663085). Interacts with CHMP1B (PubMed:20663085). Interacts with VPS2.2 (PubMed:22010978). No visible phenotype under normal growth conditions, but double mutants chmp1a and chmp1b show embryo development defect. Belongs to the SNF7 family.