Define functions of magnesium - Macro minerals?

Like Ca, Mg too has a role in bone formation. Soft tissue magnesium functions as a cofactor of many enzymes involved in energy metabolism, protein synthesis, RNA and DNA synthesis, and maintenance of the electrical potential of nervous tissues and cell membranes. Of particular importance with respect to the pathological effects of magnesium depletion, is the role of this element in regulating potassium fluxes and its involvement in the metabolism of calcium. Some of the important functions of Mg are listed below:

1) Between 50% and 60% of body magnesium is located within bone, where it is thought to form a surface constituent of the hydroxyapatite (calcium phosphate) mineral component. Initially, much of this magnesium is readily exchangeable with serum and therefore represents a moderately accessible magnesium store which can be drawn on in times of deficiency.

2) Within cells, Mg is bound to phospholipids of the cell membrane (plasma, mitochondria, endoplasmic reticulum). It helps in membrane stabilization.

3) Mg is responsible for the structural integrity of the subunits forming ribosome. It also maintains double helical structure of DNA.

4) Intracellular free Mg⁺² regulate ion movements. It modulates ion transport systems such as Ca pumps and Na-K-ATPase. These are most sensitive to depletion of body Mg⁺² levels. The impaired activity of these ion pumps is likely to be responsible for the neuromuscular problems that are present during Mg deficiency. The defects would involve difficulty in maintaining the normal movements of Ca, sodium, potassium ions required for nerve conductions.

5) Mg is vital for energy production as it is required by - ATP synthesizing protein in the mitochondria.

6) As intracellular component, it is essential for different enzyme reactions, as structural cofactor or an allosteric activator of enzyme activity.