Vacuolar-ATPase

Vacuolar-H⁺-ATPase is an enzyme complex found in organelles such as lysosomes and endosomes and in plasma membranes of eukaryotes. These V-ATPases couple the energy generated from ATP hydrolysis to pump protons across the membranes. They can serve many functions such as Ca²⁺ uptake, pH homeostasis and coupled transport. They have two domains V₀ and V₁ like the mitochondrial ATP synthase complexes (F₀ and F₁ domains). The V₀ domain has five subunits and V₁ has eight subunits. Of these, the S1 subunit of V₀ domain is missing in all apicomplexans. The subunit H of V₁ domain present in Toxoplasma gondii is missing in Cryptosporidium genomes.