SUMMARY PARAGRAPH for VMA5
VMA5 encodes the C subunit of the yeast V-ATPase V1 domain (2, 1). 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 3, 4, 5 and 6.
The vma5 null mutant is viable but lacks vacuolar (H )-ATPase activity, cannot grow at neutral pH, and is sensitive to high or low calcium levels in the medium (2, 1). Vma5p is required for the V1 domain to assemble onto the vacuolar membrane (2, 1).
Last updated: 2000-05-15