Produces ATP from ADP in the presence of a proton gradient across the membrane. The alpha chain is a regulatory subunit. ATP + 4 H(+)(in) + H2O = ADP + 5 H(+)(out) + phosphate F-type ATPases have 2 components, CF(1) - the catalytic core - and CF(0) - the membrane proton channel. CF(1) has five subunits: alpha(3), beta(3), gamma(1), delta(1), epsilon(1). CF(0) has three main subunits: a(1), b(2) and c(9-12). The alpha and beta chains form an alternating ring which encloses part of the gamma chain. CF(1) is attached to CF(0) by a central stalk formed by the gamma and epsilon chains, while a peripheral stalk is formed by the delta and b chains. Induced by a decrease in external pH from 7.5 to 5.7. Belongs to the ATPase alpha/beta chains family.