V-ATPase

Membrane-spanning region of the V-type sodium ATPase from Enterococcus hirae. Calculated hydrocarbon boundaries of the lipid bilayer are shown by red and blue dots
Identifiers
Symbol	ATP-synt_C
Pfam	PF00137
InterPro	IPR002379
PROSITE	PDOC00526
SCOP	1aty
SUPERFAMILY	1aty
OPM superfamily	5
OPM protein	2bl2
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

V-ATPase_C
crystal structure of subunit C (vma5p) of the yeast v-atpase
Identifiers
Symbol	V-ATPase_C
Pfam	PF03223
InterPro	IPR004907
SCOP	1u7l
SUPERFAMILY	1u7l
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

vATP-synt_AC39
crystal structure of subunit C (yeast subunit d) of v-atpase
Identifiers
Symbol	vATP-synt_AC39
Pfam	PF01992
InterPro	IPR002843
SCOP	1r5z
SUPERFAMILY	1r5z
Available protein structures: Pfam structures PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

Vacuolar-type H+
-ATPase (V-ATPase) is a highly conserved evolutionarily ancient enzyme with remarkably diverse functions in eukaryotic organisms. V-ATPases acidify a wide array of intracellular organelles and pump protons across the plasma membranes of numerous cell types. V-ATPases couple the energy of ATP hydrolysis to proton transport across intracellular and plasma membranes of eukaryotic cells. It is generally seen as the polar opposite of ATP synthase because ATP synthase is a proton channel that uses the energy from a proton gradient to produce ATP. V-ATPase however, is a proton pump that uses the energy from ATP hydrolysis to produce a proton gradient.

V-ATPases are found within the membranes of many organelles, such as endosomes, lysosomes, and secretory vesicles, where they play a variety of roles crucial for the function of these organelles. For example, the proton gradient across the yeast vacuolar membrane generated by V-ATPases drives calcium uptake into the vacuole through an H+
/Ca2+
antiporter system (Ohya, 1991). In synaptic transmission in neuronal cells, V-ATPase acidifies synaptic vesicles.Norepinephrine enters vesicles by V-ATPase.

V-ATPases are also found in the plasma membranes of a wide variety of cells such as intercalated cells of the kidney, osteoclasts (bone resorbing cells), macrophages, neutrophils, sperm, midgut cells of insects, and certain tumor cells. Plasma membrane V-ATPases are involved in processes such as pH homeostasis, coupled transport, and tumor metastasis. V-ATPases in the acrosomal membrane of sperm acidify the acrosome. This acidification activates proteases required to drill through the plasma membrane of the egg. V-ATPases in the osteoclast plasma membrane pump protons onto the bone surface, which is necessary for bone resorption. In the intercalated cells of the kidney, V-ATPases pump protons into the urine, allowing for bicarbonate reabsorption into the blood.