H+-ATPase

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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 ?
Salt-induced transcriptional activation of V-ATPase subunits A, B, E, and c have been shown in common ice plant [2, 6, 19].
Endogenous oscillations of the transcript amounts of subunit-c of the V-ATPase of Mesembryanthemum crystallinum with harmonic frequency resonances under continuous illumination.
The V-ATPase V0 domain, for example, which is equivalent to the F-APTase F0 domain, is not an open proton channel (Zhang et al.
The Vacuolar or V-ATPase Proton Pump: Biological Functions
Here we present a three-dimensional molecular rendering of the surface structure, presumably V-ATPase, reflecting an individual SV, rather than the average of many SVs.
Identification of V-ATPase transcripts in squid neuronal tissues
The V-ATPase creates an electrochemical proton gradient across the tonoplast, which is used for secondary-active solute uptake mediated by specific transporters, as well as is pivotal to pH homeostasis of the cytoplasm.
Distribution and Characteristics of V-ATPase in Plants
In experiments measuring the effect of DCCD (N,N'-dicyclohexylcarbodiimide) on V-ATPase activity, membrane protein was pre-incubated with DCCD at 22 [degrees] C for 10 min and assays were carried out in glass tubes.
2005) showed that V-ATPase is of direct and central importance in these proton transactions.
Electron immunohistochemistry revealed that V-ATPase immunoreactivity resides in the plasma membranes of the microvilli.
For example, investigation of the maximum likelihood landscape of 18S rRNA and V-ATPase A-subunit phylogenies suggests that the grouping of microsporidia either with the fungi (3, 4, 5) or close to the root of the archaeal domain (e.