Relationship between Total and Free Cellular Mg2+ during Metabolic Stimulation of Rat Cardiac Myocytes and Perfused Hearts

Fatholahi, Marjan; LaNoue, Kathryn F.; Romani, Andrea; Scarpa, Antonio

doi:10.1006/abbi.1999.1619

Cited by 62 publications

(45 citation statements)

References 37 publications

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“…Reports indicate that Mg 2þ concentrations can change depending on the cell compartment (31) and phase of the cell cycle (11,32). Specifically, nuclear concentrations of Mg 2þ increase substantially during mitosis (11).…”

Section: Discussionmentioning

confidence: 99%

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Masterson

Shi

Metcalfe

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

138

220

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Protein kinase A (PKA) is a ubiquitous phosphoryl transferase that mediates hundreds of cell signaling events. During turnover, its catalytic subunit (PKA-C) interconverts between three major conformational states (open, intermediate, and closed) that are dynamically and allosterically activated by nucleotide binding. We show that the structural transitions between these conformational states are minimal and allosteric dynamics encode the motions from one state to the next. NMR and molecular dynamics simulations define the energy landscape of PKA-C, with the substrate allowing the enzyme to adopt a broad distribution of conformations (dynamically committed state) and the inhibitors (high magnesium and pseudosubstrate) locking it into discrete minima (dynamically quenched state), thereby reducing the motions that allow turnover. These results unveil the role of internal dynamics in both kinase function and regulation.allostery | cooperativity | phospholamban | substrate recognition | intrinsically disordered proteins

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Section: Discussionmentioning

confidence: 99%

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Masterson

Shi

Metcalfe

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

138

220

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“…In these experiments, changes in cAMP were used to alter cytosolic magnesium levels pharmacologically, with impact both on magnesium and sodium transport. cAMP has been shown to stimulate Mg 2ϩ /Na ϩ exchange in several tissues, including the ruminal epithelium, thereby decreasing intracellular Mg 2ϩ (3,10,23,25).…”

mentioning

confidence: 99%

Basolateral Mg²⁺/Na⁺ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg²⁺

Leonhard-Marek¹,

Stumpff²,

Brinkmann³

et al. 2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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High potassium diets lead to an inverse regulation of sodium and magnesium absorption in ruminants, suggesting some form of cross talk. Previous Ussing chamber experiments have demonstrated a divalent sensitive Na(+) conductance in the apical membrane of ruminal epithelium. Using patch-clamped ruminal epithelial cells, we could observe a divalent sensitive, nonselective cation conductance (NSCC) with K(+) permeability > Cs(+) permeability > Na(+) permeability. Conductance increased and rectification decreased when either Mg(2+) or both Ca(2+) and Mg(2+) were removed from the internal or external solution or both. The conductance could be blocked by Ba(2+), but not by tetraethylammonium (TEA). Subsequently, we studied this conductance measured as short-circuit current (I(sc)) in Ussing chambers. Forskolin, IBMX, and theophylline are known to block both I(sc) and Na transport across ruminal epithelium in the presence of divalent cations. When the NSCC was stimulated by removing mucosal calcium, an initial decrease in I(sc) was followed by a subsequent increase. The cAMP-mediated increase in I(sc) was reduced by low serosal Na(+) and serosal addition of imipramine or serosal amiloride and depended on the availability of mucosal magnesium. Luminal amiloride had no effect. Flux studies showed that low serosal Na(+) reduced (28)Mg fluxes from mucosal to serosal. The data suggest that cAMP stimulates basolateral Na(+)/Mg(2+) exchange, reducing cytosolic Mg. This increases sodium uptake through a magnesium-sensitive NSCC in the apical membrane. Likewise, the reduction in magnesium uptake that follows ingestion of high potassium fodder may facilitate sodium absorption, as observed in studies of ruminal osmoregulation. Possibly, grass tetany (hypomagnesemia) is a side effect of this useful mechanism.

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“…Free ionized Mg 2ϩ concentrations remain relatively unchanged in mammalian cells, whereas total concentrations can vary to a considerable extent, mostly depending on the intracellular ion milieu and on metabolic stimulation by hormones and other factors (1,3). Cells of the yeast Saccharomyces cerevisiae tightly control intracellular Mg 2ϩ levels, which remain relatively constant in growth media containing 1-100 mM Mg 2ϩ .…”

Section: Mgmentioning

confidence: 99%

The Yeast Plasma Membrane Protein Alr1 Controls Mg2+ Homeostasis and Is Subject to Mg2+-dependent Control of Its Synthesis and Degradation

Graschopf

Stadler

Hoellerer

et al. 2001

Journal of Biological Chemistry

112

113

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Relationship between Total and Free Cellular Mg2+ during Metabolic Stimulation of Rat Cardiac Myocytes and Perfused Hearts

Cited by 62 publications

References 37 publications

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Basolateral Mg²⁺/Na⁺ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg²⁺

The Yeast Plasma Membrane Protein Alr1 Controls Mg2+ Homeostasis and Is Subject to Mg2+-dependent Control of Its Synthesis and Degradation

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Relationship between Total and Free Cellular Mg2+ during Metabolic Stimulation of Rat Cardiac Myocytes and Perfused Hearts

Cited by 62 publications

References 37 publications

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Dynamically committed, uncommitted, and quenched states encoded in protein kinase A revealed by NMR spectroscopy

Basolateral Mg2+/Na+ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg2+

The Yeast Plasma Membrane Protein Alr1 Controls Mg2+ Homeostasis and Is Subject to Mg2+-dependent Control of Its Synthesis and Degradation

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Basolateral Mg²⁺/Na⁺ exchange regulates apical nonselective cation channel in sheep rumen epithelium via cytosolic Mg²⁺