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 ?
During acidification, H+ is transported into secondary lysosomes by vacuolar type H+ adenosine triphosphatase (V-ATPase), and TCIRG1 encodes its a3 subunit.[1]
Another reason for our results would be the increased expression of a3 and d2 subunits of vacuolar-type H + adenosine triphosphatase (V-ATPase), which accelerates intracellular acidification when activated and increases bone resorption capability of osteoclasts (Liu et al., 2016).
The intraluminal space of the endosome and lysosome is acidified by vacuolar-type [H.sup.+] ATPase (V-ATPase) at the endosomal membrane.
Mutating subunits of the vacuolar proton-translocating ATPase (v-ATPase) leads to increased vacuolar pH and accelerated aging (Figure 2(a)).
Two types of [H.sup.+] pumps are present in the vacuolar membrane: vacuolar type [H.sup.+]-ATPase (V-ATPase) and the vacuolar pyrophosphatase (V-PPase) [21-23].
The acidic pH that mediates these important viral process is established and maintained by the cell's vacuolar-type H+ ATPase (V-ATPase) proton pump.
Salt-induced transcriptional activation of V-ATPase subunits A, B, E, and c have been shown in common ice plant [2, 6, 19].
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.
V-ATPase and [H.sup.+]-translocating inorganic pyrophosphatase (V-PPase) [21], the former is dominant and indispensable for the plant growth under normal conditions.
The [H.sup.+]-ATPases on the plasma membrane (PM-ATPase) and vacuolar membrane (V-ATPase) have been shown to hydrolyze ATP and acidify the apoplast and vacuolar lumen, respectively.
(2005) showed that V-ATPase is of direct and central importance in these proton transactions.