Ultracytochemical evidence for a proton-pump adenosine triphosphatase in chick osteoclasts.
The distribution of Mg++-ATPase in osteoclasts along the endosteal surface of the chick tibia was investigated by neutral and alkaline pH cytochemical methods at the electron-microscopic level. Reaction product was observed in mitochondria, cytoplasmic vesicles, and ruffled-border membrane. Levamisole, ouabain, and vanadate did not affect the enzymatic activity. Para-chloromercuribenzoic acid (PCMB) prevented staining of mitochondria, ruffled border, and most cytoplasmic vesicles. Tri-n-butyltin decreased the amount of reaction product in cytoplasmic vesicles and ruffled-border membrane, but did not inhibit reaction product formation within mitochondria. Duramycin, which is a potent inhibitor for proton-pump ATPase, blocked reaction-product formation along the ruffled-border membrane, in mitochondria, and in cytoplasmic vesicles at alkaline pH, but not at neutral pH. It is concluded that the alkaline pH method for Mg++-ATPase appears to demonstrate sites of proton-pump ATPase activity.
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism*; D002645:Chickens; D006651:Histocytochemistry; D007700:Kinetics; D008854:Microscopy, Electron; D008871:Microvilli / Q000201:enzymology / Q000648:ultrastructure; D008928:Mitochondria / Q000201:enzymology / Q000648:ultrastructure; D010010:Osteoclasts / Q000201:enzymology* / Q000648:ultrastructure
D017301:Ca(2+) Mg(2+)-ATPase