Rab9-regulated ATPase required for endosome to Golgi transport. Involved in transport vesicle docking at the Golgi complex, possibly by participating in release M6PRBP1/TIP47 from vesicles to permit their efficient docking and fusion at the Golgi. Specifically binds Rab9, but not other Rab proteins. Has low intrinsic ATPase activity due to autoinhibition, which is relieved by Rab9.