Characterization of proton transport in bone-derived membrane vesicles

ATP-dependent proton transport was characterized in membrane vesicles, prepared by differential centrifugation from medullary bone of egg laying hens, a source rich in osteoclasts. The H(+)-ATPase present in this preparation showed the characteristics of a vacuolar H(+)-ATPase in its sensitivity to inhibitors, including bafilomycin A1, its sensitivity to cold treatment and its electrogenic mechanism. There was no evidence for a direct activation of the H(+)-ATPase by anions, including Cl-. These results are consistent with the view that the osteoclast, the cell responsible for bone resorption, secrets acid by means of a vacuolar H(+)-ATPase.