InterPro domain: IPR038497

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 the C-terminal domain of subunit H (also known as Vma13p) found in the V1 complex of V-ATPases. This subunit has a regulatory function, being responsible for activating ATPase activity and coupling ATPase activity to proton flow [ 3 ]. The yeast enzyme contains five motifs similar to the HEAT or Armadillo repeats seen in the importins, and can be divided into two distinct domains: a large N-terminal domain consisting of stacked alpha helices, and a smaller C-terminal alpha-helical domain with a similar superhelical topology to an armadillo repeat [ 4 ].

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. Structure and assembly of the yeast V-ATPase. J. Bioenerg. Biomembr. 35, 301-12
4. Crystal structure of the regulatory subunit H of the V-type ATPase of Saccharomyces cerevisiae. Proc. Natl. Acad. Sci. U.S.A. 98, 7134-9