H+-ATPase

H+-ATPase

A ubiquitously expressed enzyme transporter present in the plasma membrane, as well as in endomembrane organelles—vacuoles, lysosomes, endosomes, the Golgi apparatus, chromaffin granules and coated vesicles—which acidifies intracellular compartments in eukaryotic cells. Acidification is necessary for such intracellular processes as protein sorting, protein degradation and coupled transport, zymogen activation, receptor-mediated endocytosis and synaptic vesicle proton gradient generation; it also plays a role in bone reabsorption and in sperm motility and maturation. H+-ATPase is a multisubunit complex composed of two domains: a cytosolic V1 domain responsible for ATP hydrolysis and a transmembrane V0 domain responsible for protein translocation.

Mechanisms of regulating H+-ATPase activity:
• Recycling of H+-ATPase-containing vesicles to and from the plasma membrane;
• Glucose-sensitive assembly/disassembly of the holoenzyme complex.
 
Molecular pathology
H+-ATPase mutations in the A3 gene cause recessive osteopetrosis; they have been implicated in tumour metastasis.
References in periodicals archive ?
1995, "A bovine cDNA and a yeast gene (VMA 8) encoding the subunit D of the vacuolar H+-ATPase," Proc.
2000, "Cloning, expression and crystallization of VMA13p, an essential subunit of the vacuolar H+-ATPase of Saccharomyces cerevisiae," Acta Crystallographica, 56, pp.
1999, "cDNA and genomic cloning of sugar beet V-type H+-ATPase subunit A and c isoforms: evidence for co-ordinate expression during plant development and co-ordinate induction in response to high salinity," Plant Mol.