V/A-type ATP synthase catalytic subunit A. These ATPases couple ATP hydrolysis to the build up of a H+ gradient, but V-type ATPases do not catalyze the reverse reaction. Vacuolar (V-type) ATPases play major roles in endomembrane and plasma membrane proton transport in eukaryotes. They are found in multiple intracellular membranes including vacuoles, endosomes, lysosomes, Golgi-derived vesicles, secretory vesicles, as well as the plasma membrane. Archaea have a protein which is similar in sequence to V-ATPases, but functions like an F-ATPase (called A-ATPase). A similar protein is also found in a few bacteria.
Jiyao W et al.(2023). "The conserved domain database in 2023.",