V-type proton ATPase subunit H is an enzyme that in humans is encoded by the ATP6V1Hgene.
This gene encodes a component of vacuolar ATPase (V-ATPase), a multisubunit enzyme that mediates acidification of eukaryotic intracellular organelles. V-ATPase dependent organelle acidification is necessary for such intracellular processes as protein sorting, zymogen activation, receptor-mediated endocytosis, and synaptic vesicle proton gradient generation. V-ATPase is composed of a cytosolic V1 domain and a transmembrane V0 domain. The V1 domain consists of three A and three B subunits, two G subunits plus the C, D, E, F, and H subunits. The V1 domain contains the ATP catalytic site. The V0 domain consists of five different subunits: a, c, c', c", and d. Additional isoforms of many of the V1 and V0 subunit proteins are encoded by multiple genes or alternatively spliced transcript variants. This gene encodes the regulatory H subunit of the V1 domain which is required for catalysis of ATP but not the assembly of V-ATPase. Three alternatively spliced transcript variants encode two isoforms of the H subunit.
Geyer M, Yu H, Mandic R, et al. (2002). "Subunit H of the V-ATPase binds to the medium chain of adaptor protein complex 2 and connects Nef to the endocytic machinery.". J. Biol. Chem.277 (32): 28521–9. doi:10.1074/jbc.M200522200. PMID12032142.
Lu M, Vergara S, Zhang L, et al. (2002). "The amino-terminal domain of the E subunit of vacuolar H(+)-ATPase (V-ATPase) interacts with the H subunit and is required for V-ATPase function.". J. Biol. Chem.277 (41): 38409–15. doi:10.1074/jbc.M203521200. PMID12163484.