Localization of subunit C (Vma5p) in the yeast vacuolar ATPase by immuno electron microscopy

Vacuolar ATPases (V 1 V 0 ‐ATPases) function in proton translocation across lipid membranes of subcellular compartments. We have used antibody labeling and electron microscopy to define the position of subunit C in the vacuolar ATPase from yeast. The data show that subunit C is binding at the interface of the ATPase and proton channel, opposite from another stalk density previously identified as subunit H [Wilkens S., Inoue T., and Forgac M. (2004) Three‐dimensional structure of the vacuolar ATPase – Localization of subunit H by difference imaging and chemical cross‐linking. J. Biol. Chem. 279, 41942–41949]. A picture of the vacuolar ATPase stalk domain is emerging in which subunits C and H are positioned to play a role in reversible enzyme dissociation and activity silencing.