The Mechanism of Ion Translocation in Mitochondria

摘要: The translocation of Ca2+ across the mitochondrial membrane in absence metabolism has been studied. experimental system consists coupling downhill efflux K+ from rotenone-valinomycin treated mitochondria to uphill influx Ca2+. The Vmax driven uptake is 4 μg ions protein−1μsec−1. rate following properties: it insensitive oligomycin, cyanide or antimycin A; dependent on concentration and valinomycin, external abolished above 13 mM Ko; shows a saturation kinetics. The Ca+ inhibited by several agents, among which La3+, H+, dinitrophenol, Mg2+ Na+. Except case Na+ inhibition found be competitive type. Apparent Ki were order 50 nM for 3 μM 0.3 H+ Mg2+. La3+ appears stoichiometric with protein: 50% occurs at nmoles La3+μg protein−1. Inhibition aerobic release require larger amount La3+. Binding experiments indicate that contain sensitive sites corresponding 400 nmoles/g protein. binding additive caused dinitrophenol not affected treatments reduce surface binding, such as addition impermeant cations depletion phospholipids. At variance sites, are phospholipids cations. A model discussed assumes fluxes coupled together through operation common chemical translocator. carrier suggested also responsible linked Ca2+.