InterPro domain: IPR036906

V-ATPases (also known as V1V0-ATPase or vacuolar ATPase) are found in the eukaryotic endomembrane system, and in the plasma membrane of prokaryotes and certain specialised eukaryotic cells. V-ATPases hydrolyse ATP to drive a proton pump, and are involved in a variety of vital intra- and inter-cellular processes such as receptor mediated endocytosis, protein trafficking, active transport of metabolites, homeostasis and neurotransmitter release [ 1 ]. V-ATPases are composed of two linked complexes: the V1 complex (subunits A-H) contains the catalytic core that hydrolyses ATP, while the V0 complex (subunits a, c, c', c'', d) forms the membrane-spanning pore. V-ATPases may have an additional role in membrane fusion through binding to t-SNARE proteins [ 2 ].

This entry represents subunit F in the V1 complex of V-ATPases and Na(+)-translocating ATPase in Enterococcus hirae. Subunit F is a 16kDa protein that is required for the assembly and activity of V-ATPase, and has a potential role in the differential targeting and regulation of the enzyme for specific organelles. This subunit is not necessary for the rotation of the ATPase V1 rotor, but it does promote catalysis [ 3 ]. In Enterococcus hirae, Na(+)-translocating ATPase extrudes sodium ions from the cytoplasm and generates the Na+ electrochemical gradient by using the energy of ATP [ 4 ]. Structurally, the subunit F is composed of three layers (alpha/beta/alpha) with parallel beta-sheet of four strands.

1. A structural model of the vacuolar ATPase from transmission electron microscopy. Micron 36, 109-26
2. A new view of an old pore. Cell 121, 496-7
3. The F subunit of Thermus thermophilus V1-ATPase promotes ATPase activity but is not necessary for rotation. J. Biol. Chem. 279, 18085-90
4. Catalytic properties of Na(+)-translocating V-ATPase in Enterococcus hirae. Biochim. Biophys. Acta 1505, 75-81