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 ?
Sabatini, "mTORC1 senses lysosomal amino acids through an inside-out mechanism that requires the vacuolar H+-ATPase," Science, vol.
Martinez et al., "Vacuolar H+-ATPase in human breast cancer cells with distinct metastatic potential: distribution and functional activity," American Journal of Physiology, vol.
P Geibel, "Renal vacuolar H+-ATPase," Physiological Reviews, vol.
Kane, "The long physiological reach of the yeast vacuolar H+-ATPase," Journal of Bioenergetics and Biomembranes, vol.
Novel Vacuolar H+-ATPase Complexes Resulting from Overproduction of Vma5p and Vma13p.
The vacuolar H+-ATPase: a universal proton pump of eukaryotes.
Defined sites of interaction between subunits E (Vma4p), C (Vma5p), and G (Vma10p) within the stator structure of the vacuolar H+-ATPase. Biochemistry, vol.
The V-type H+-ATPase in vesicular trafficking: targeting, regulation and function.
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W., 2000, "Cloning, expression and crystallization of VMA13p, an essential subunit of the vacuolar H+-ATPase of Saccharomyces cerevisiae," Acta Crystallographica, 56, pp.
[76] Lehr, A., Kirsch, M., Viereck, R., Schiemann, J., and Rausch, T., 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.
[17] Nelson, N., and Taiz, L., 1989, "The evolution of H+-ATPases," Trends in Biol.