Stopped-flow fluorimetry using voltage-sensitive fluorescent membrane probes

Australian Research Counci

Glucocorticoid receptor stabilization: Relative effects of molybdate ion on inactivation by alkaline phosphatase and phospholipase A2

Glucocorticoid receptors in cytosol preparations from rat liver or mouse L cells are inactivated by phospholipase A2 or calf intestine alkaline phosphatase. Molybdate ion, an inhibitor of a variety of phosphatase enzymes, does not prevent inactivation of glucocorticoid binding capacity by alkaline phosphatase but it blocks inactivation by phospholipase A2. In neither case is the enzyme itself inhibited, and the effect of molybdate on phospholipase-mediated inactivation appears to reflect the ability of molybdate to prevent receptor inactivation by the detergent action of lysophosphatides.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25367/1/0000816.pd

Accumulation of calcium and phosphate stimulated by carboxylic antibiotics into mitochondria

Carboxylic ionophores such as nigericin, dianemycin, the monensins and compounds Lilly A 217 or X-537 A, stimulate an electron-transport dependent accumulation of Ca 2+ and phosphate into mitochondria. Ion accumulation is stimulated under conditions of limited Ca 2+ loading imposed by phosphate in the presence of β-hydroxybutyrate. Carboxylic ionophores do not affect divalent ion uptake when β-hydroxybutyrate is replaced for by succinate. They block Ca 2+ and phosphate accumulation when energy is provided from the hydrolysis of ATP, or from the oxidation of glutamate, α-ketoglutarate, pyruvate or glutamate+malate. Nigericin-like antibiotics also transform the indefinite prolongation of state 3 respiration induced by Ca 2+ and phosphate on β-hydroxybutyrate oxidation, into tightly coupled state 3 to 4 transitions. Evidence suggests that electrophoretic Ca 2+ transport occurs in parallel with proton or K + carriers. The anion movements associated to Ca 2+ uptake are most probably driven by the existent ΔpH across the mitochondrial membrane.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44799/1/10863_2005_Article_BF01516075.pd