Journal of Membrane Biology 1999-07-01

Characterization of a P-type copper-stimulated ATPase from mouse liver.

K Takeda, M Ushimaru, Y Fukushima, M Kawamura

Index: J. Membr. Biol. 170(1) , 13-6, (1999)

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Abstract

Mouse liver microsomes treated with octylthioglucoside (OTG-microsomes) were examined for copper-stimulated ATPase activity. The activity was about 1 micromol Pi/mg protein/hr under optimal conditions [300 mM KCl, 3 mm MgSO4, 10 mM GSH, 0.5 micron CuSO4, 3 mM ATP and 50 mM acetate buffer at pH5.0]. A reducing agent such as GSH or dithiothreitol was required for the activity, and removal of Cu+ from the reaction mixture by bathocuporinedisulfonate resulted in a complete loss of copper-stimulated ATPase activity. Vanadate inhibited the copper-stimulated ATPase activity. The OTG-microsomes were phosphorylated in a hydroxylamine-sensitive and copper-stimulated way. Iron used instead of copper also stimulated both ATPase and phosphorylation. These results suggest that microsomes from mouse liver contain copper/iron-stimulated P-type ATPase.