VMA7 encodes the F subunit of the yeast V-ATPase V₁ domain (1, 3). Vacuolar (H )-ATPases (V-ATPases) are ATP-dependent proton pumps that have been identified in many eukaryotes, where they acidify intracellular vacuolar compartments. Vacuolar acidification is important for many cellular processes, including endocytosis, targeting of newly synthesized lysosomal enzymes, and other molecular targeting processes. The V-ATPase consists of two separable domains. The V₁ domain has eight known subunits, is peripherally associated with the vacuolar membrane, and catalyzes ATP hydrolysis. The V₀ domain is an integral membrane structure of five subunits, and transports protons across the membrane. The structure, function, and assembly of V-ATPases are reviewed in references 2, 4, 5 and 6.

The vma7 null mutant is viable but lacks vacuolar (H )-ATPase activity, cannot grow at neutral pH, and fails to accumulate quinacrine in the vacuole (1, 3). The remaining V₁ subunits are present at normal levels but are not assembled onto the vacuolar membrane in the vma7 null mutant; V₀ subunit levels are reduced in the vma7 null (1, 3). A specific interaction between Vma7p and the V-ATPase D subunit (Vma8p) has been detected (7).

Last updated: 2000-05-16