VATPase_H, regulatory vacuolar ATP synthase subunit H (Vma13p); activation component of the peripheral V1 complex of V-ATPase, a heteromultimeric enzyme which uses ATP to actively transport protons into organelles and extracellular compartments. The topology is that of a superhelical spiral, in part the geometry is similar to superhelices composed of armadillo repeat motifs, as found in importins for example.