Multisubunit vacuolar-type proton pumps, or H(+)-ATPases, acidify various intracellular compartments, such as vacuoles, clathrin-coated and synaptic vesicles, endosomes, lysosomes, and chromaffin granules. H(+)-ATPases are also found in plasma membranes of specialized cells, where they play roles in urinary acidification, bone resorption, and sperm maturation. Multiple subunits form H(+)-ATPases, with proteins of the V1 class hydrolyzing ATP for energy to transport H+, and proteins of the V0 class forming an integral membrane domain through which H+ is transported. ATP6V0E2 encodes an isoform of the H(+)-ATPase V0 e subunit, an essential proton pump component (Blake-Palmer et al., 2007 [PubMed 17350184]).[supplied by OMIM, Mar 2008].