VMA6 encodes the d subunit of the yeast V-ATPase V₀ domain (1). Vacuolar (H )-ATPases (V-ATPases) are ATP-dependent proton pumps that 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, 3, 4 and 5.

The vma6 null mutant is viable but shows a growth defect at neutral pH and is sensitive to calcium (1). In the absence of Vma6p, the remaining V₀ subunits are destabilized and the V₁ domain does not assemble onto the vacuolar membrane (1).

V-ATPases have been identified in numerous eukaryotes (2, 5); Vma6p homologs have been identified in red beet and Arabidopsis (6).

Last updated: 2000-05-17