Defining steps in RAVE-catalyzed V-ATPase assembly using purified RAVE and V-ATPase subcomplexes.

The vacuolar H-ATPase (V-ATPase) is a highly conserved proton pump responsible for the acidification of intracellular organelles in virtually all eukaryotic cells. V-ATPases are regulated by the rapid and reversible disassembly of the peripheral V domain from the integral membrane V domain, accompanied by release of the V C subunit from both domains. Efficient reassembly of V-ATPases requires the Regulator of the H-ATPase of Vacuoles and Endosomes (RAVE) complex in yeast.

Molecular Interactions and Cellular Itinerary of the Yeast RAVE (Regulator of the H+-ATPase of Vacuolar and Endosomal Membranes) Complex.

The RAVE complex (regulator of the H(+)-ATPase of vacuolar and endosomal membranes) is required for biosynthetic assembly and glucose-stimulated reassembly of the yeast vacuolar H(+)-ATPase (V-ATPase). Yeast RAVE contains three subunits: Rav1, Rav2, and Skp1. Rav1 is the largest subunit, and it binds Rav2 and Skp1 of RAVE; the E, G, and C subunits of the V-ATPase peripheral V1 sector; and Vph1 of the membrane Vo sector.

Loss of vacuolar H+-ATPase activity in organelles signals ubiquitination and endocytosis of the yeast plasma membrane proton pump Pma1p.

Yeast mutants lacking the intracellular V-ATPase proton pump (vma mutants) have reduced levels of the Pma1p proton pump at the plasma membrane and increased levels in organelles including the vacuolar lumen. We examined the mechanism and physiological consequences of Pma1p mislocalization. Pma1p is ubiquitinated in vma mutants, and ubiquitination depends on the ubiquitin ligase Rsp5p and the arrestin-related adaptor protein Rim8p.

The RAVE complex is an isoform-specific V-ATPase assembly factor in yeast.

The regulator of ATPase of vacuoles and endosomes (RAVE) complex is implicated in vacuolar H(+)-translocating ATPase (V-ATPase) assembly and activity. In yeast, rav1 mutants exhibit a Vma(-) growth phenotype characteristic of loss of V-ATPase activity only at high temperature. Synthetic genetic analysis identified mutations that exhibit a full, temperature-independent Vma(-) growth defect when combined with the rav1 mutation.

Consequences of loss of Vph1 protein-containing vacuolar ATPases (V-ATPases) for overall cellular pH homeostasis.

In yeast cells, subunit a of the vacuolar proton pump (V-ATPase) is encoded by two organelle-specific isoforms, VPH1 and STV1. V-ATPases containing Vph1 and Stv1 localize predominantly to the vacuole and the Golgi apparatus/endosomes, respectively. Ratiometric measurements of vacuolar pH confirm that loss of STV1 has little effect on vacuolar pH.