The effects of membrane potential and lanthanides on the conformation of the Ca2+-transport ATPase in sarcoplasmic reticulum.

摘要: The effects of Ca2+, lanthanide ions (Gd3+, La3+ and Pr3+) membrane potential on the fluorescence tryptophan covalently bound fluorescein were analysed in native isothiocyanate (FITC)-labelled sarcoplasmic reticulum vesicles. binding Ca2+ lanthanides to Ca2+-ATPase increases intensity decreases FITC; dependence these cation concentration is consistent with involvement high-affinity Ca2+-binding sites cation-induced changes. FITC-labelled vesicles also influenced by changes induced ion substitution. Inside positive increases, while inside negative decreases, FITC. Smaller potential-dependent observed. FITC are discussed terms two major conformations (E1 E2), that assumed alternate during transport. observations support suggestion [Dux, Taylor, Ting-Beall & Martonosi (1985) J. Biol. Chem. 260, 11730-11743] vanadate-induced crystals represent E2, lanthanide-induced E1, conformation enzyme.