title: Adenosine triphosphatases associated with bovine brain microtubules. II. Properties of ATPases I and II.
abstract: The catalytic properties of two ATPases which had been purified from bovine brain microtubules (Tominaga, S. & Kaziro, Y. (1983) J. Biochem. 93, 1085-1092) were studied. ATPase I, which had a molecular weight of 33,000, required the presence of 1.0 microM tubulin, 0.2 mM Mg2+, and 10 mM Ca2+ for maximal activity. The activation of ATPase I by tubulin was specific to the native form of tubulin, which could not be replaced by F-actin or tubulin denatured either by heat or more mildly by dialysis in the absence of glycerol. ATPase I was not specific to ATP, and GTP, and to a lesser extent, UTP and CTP were also hydrolyzed. Km for ATP of ATPase I was about 0.04 mM. ATPase I was inhibited by 5 mM Mg2+, 0.04 M K+, 10(-3) M vanadate, 10 mM N-ethylmaleimide, or 20% (v/v) glycerol. ATPase II, which was associated with membrane vesicles, required the presence of 0.2-2.0 mM Mg2+ and 20 mM KCl for activity. Tubulin stimulated the reaction of ATPase II only partially, and the addition of Ca2+ was rather inhibitory. ATPase II was specific to ATP with a Km value of 0.14 mM. It was inhibited by 1.6 mM N-ethylmaleimide and 20% (v/v) glycerol, but was not very sensitive to vanadate. Instead, ATPase II was inhibited by trifluoperazine, chlorpromazine, and nicardipin at 10(-3) M.
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis* / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000201:enzymology*; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002855:Chromatography, Thin Layer; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008870:Microtubules / Q000201:enzymology*; D011189:Potassium Chloride / Q000494:pharmacology; D013379:Substrate Specificity; D014404:Tubulin / Q000378:metabolism
chemical_list: D014404:Tubulin; D011189:Potassium Chloride; D000251:Adenosine Triphosphatases; D008274:Magnesium; D002118:Calcium