Protein that regulates the vacuolar V-ATPase; inhibits V1-ATPase activity and triggers ATP-dependent disassembly of the V-ATPase holoenzyme, counteracting the function of the RAVE complex; localizes to the cytoplasm; required for retention of the vacuolar-ATPase V0 domain subunit Stv1p in pre-vacuolar compartments; involved in resistance to oxidative damage; member of a conserved family of TLDc domain proteins found in eukaryotes; contains an N-terminal EF-hand-like domain