title: Purification and characterization of lysosomal H(+)-ATPase. An anion-sensitive v-type H(+)-ATPase from rat liver lysosomes.
abstract: Lysosomal H(+)-ATPase was purified to homogeneity from rat liver lysosomes. It is a bafilomycin A1-sensitive Mg(2+)-ATPase, which reacts with antibodies against the 16- and 70-kDa subunits of vacuolar H(+)-ATPase (Nezu, J., Motojima, K., Tamura, H., and Ohkuma, S. (1992) J. Biochem. (Tokyo) 112, 212-219), and has been separated from both the N-ethylmaleimide (NEM)-sensitive/bafilomycin A1-insensitive Mg(2+)-ATPase (ATPase I) and the NEM-insensitive Mg2+/Ca(2+)-ATPase (ATPase II) (Hayashi, H., Arai, K., Sato, O., Shimaya, A., Sai, Y., and Ohkuma, S. (1992) Chem. Pharm. Bull. 40, 2783-2786). The purified enzyme had the subunit structure of vacuolar H(+)-ATPase, consisting of 110-, 70-, 56-, 42-, 39-, 34-, (32-,) and 16-kDa proteins. It had optimal activity at a pH of 7.0-8.0, with an apparently single Km value for ATP of 95 microM. It hydrolyzed ATP > or = dATP >> GTP, ITP >> UTP, but not CTP, and was inhibited by ADP. It demonstrated divalent cation specificity in the order of Mg2+, Mn2+ > Fe2+, Co2+ > Ca2+. Among various anions, Cl-, Br-, and F- activated ATPase activity, whereas NO3- inhibited activity. It was inhibited not only by bafilomycin A1 but also by NEM, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, quercetin, and dicyclohexylcarbodi-imide. The purified enzyme was incorporated into proteoliposomes where its proton pump activity was reconstituted. This suggested that the isolated enzyme maintains its H+ translocation activity. These findings suggest that the isolated enzyme is an anion-sensitive vacuolar type H(+)-ATPase that functions as a lysosomal proton pump.
authors.affiliation: Department of Biochemistry, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Arai
authors.forename: A
authors.initials: A
authors.lastname: Shimaya
authors.forename: N
authors.initials: N
authors.lastname: Hiratani
authors.forename: S
authors.initials: S
authors.lastname: Ohkuma
mesh_terms: D000818:Animals; D000838:Anions; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D018942:Macrolides; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D012995:Solubility; D013379:Substrate Specificity
chemical_list: D000838:Anions; D000900:Anti-Bacterial Agents; D018942:Macrolides; C040929:bafilomycin A1; D017301:Ca(2+) Mg(2+)-ATPase; D006180:Proton-Translocating ATPases