Vta1 (VPS20-associated protein 1) is a positive regulator of Vps4. Vps4 is an ATPase that is required in the multivesicular body (MVB) sorting pathway to dissociate the endosomal sorting complex required for transport (ESCRT). Vta1 promotes correct assembly of Vps4 and stimulates its ATPase activity through its conserved Vta1/SBP1/LIP5 region [1].

1: Recycling of ESCRTs by the AAA-ATPase Vps4 is regulated by a conserved VSL region in Vta1. Azmi I, Davies B, Dimaano C, Payne J, Eckert D, Babst M, Katzmann DJ; J Cell Biol. 2006;172:705-717. PMID:16505166