The high affinity (Ca2+-Mg2+)-ATPase purified from rat liver plasma membrane (Lin, S.-H., and Fain, J. N. (1984) J. Biol. Chem. 259, 3016-3020) has been further characterized. This enzyme also possesses Mg2+-stimulated ATPase activity with K0.5 of 0.16 microM free Mg2+. However, the Vm of the Mg2+-stimulated activity is only half that of the Ca2+-stimulated ATPase activity. The effects of Ca2+ ...

Inverted membrane vesicles from strain 7, a wild type Escherichia coli K12 strain, actively transport calcium with energy supplied either by respiration or by ATP. These vesicles also have energy-linked quenching of quinacrine fluorescence. Membranes of strain 7, depleted of Mg2+ATPase by EDTA treatment, lack both activities. Membrane vesicles from strain NR70, a mutant lacking the Mg2+ATPase, ...

Mg2+ plays an important role in biological functions, similar to that of Ca2+. In terms of neural activity, it is well known that Mg2+ blocks the NMDA receptor. However, the relationship between Mg2+ and neural function has not been well understood. We have investigated the effect of low extracellular Mg2+ concentration ([Mg2+]o) on neural activity in rat cortical and hippocampal neurons by usi...

Monoclonal antibody therapies targeting the EGF receptor (EGFR) frequently result in hypomagnesemia in human patients. In contrast, EGFR tyrosine kinase inhibitors do not affect Mg2+ balance in patients and only have a mild effect on Mg2+ homeostasis in rodents at elevated doses. EGF has also been shown to affect phosphate (Pi) transport in rat and rabbit proximal convoluted tubules (PCT), but ...

Magnesium ions (Mg2+) are essential for various enzymatic reactions in the body associated with energy production and activation of the muscles and nerves. Mg2+ is also involved in blood pressure regulation, maintenance of body temperature, and glucose metabolism. Although various factors including foods and physical conditions have been reported to change serum Mg2+ status in humans, serum Mg2...

Mitochondria must maintain volume homeostasis in order to carry out oxidative phosphorylation. It has been postulated that the concentration of free Mg2+([Mg2+]) serves as the sensor of matrix volume and regulates a K+-extruding K+/H+antiport (K. D. Garlid. J. Biol. Chem. 255: 11273-11279, 1980). To test this hypothesis, the fluorescent probe furaptra was used to monitor [Mg2+] and free Ca2+ co...

A change in pH can alter the intracellular concentration of electrolytes such as intracellular Ca2+and Na2+ ([Na+]i) that are important for the cardiac function. For the determination of the role of pH in the cardiac magnesium homeostasis, the intracellular Mg2+ concentration ([Mg2+]i), membrane potential and contraction in the papillary muscle of guinea pigs using ion-selective electrodes chan...

The effect of Mg2+ on ATP-activated current in rat nodose ganglion neurons was investigated with the use of the whole cell patch-clamp technique. Mg2+ decreased the amplitude of ATP-activated current in a concentration-dependent manner over the concentration range of 0.25-8 mM, with a 50% inhibitory concentration value of 1.5 mM for current activated by 10 microM ATP. Mg2+ shifted the ATP conce...

Synthesis of the 31-amino acid, inner membrane protein MgtS (formerly denoted YneM) is induced by very low Mg2+ in a PhoPQ-dependent manner in Escherichia coli Here we report that MgtS acts to increase intracellular Mg2+ levels and maintain cell integrity upon Mg2+ depletion. Upon development of a functional tagged derivative of MgtS, we found that MgtS interacts with MgtA to increase the level...

Changes in [Mg2+] in a millimolar range have a significant inverse effect on the Ca2+- (or Sr2+)activated tension generation of skeletal muscle fibers. Single frog (Rana pipiens) semitendinosus muscle fibers were "skinned" (sarcolemma removed) and contracted isometrically in bathing solutions of varying [Ca2+] or [Sr2+] and [Mg2+] but a constant pH, [MgATP2-], [K+], [CP2-], [CPK], and ionic str...