PMID: 9151Sep 21, 1976

The interaction of magnesium ions with the calcium pump of sarcoplasmic reticulum

Biochimica Et Biophysica Acta
P J GarrahanG L Alonso

Abstract

1. In the presence of Ca2+, ATP phosphorylates the Ca2+ pump of sarcoplasmic reticulum at the same site and to the same extent regardless of whether Mg2+ is added or not to the incubation media, the main effect of added Mg2+ being to increase the rate of phosphorylation. 2. When phosphoenzyme is made in Mg2+-containing media it dephosphorylates about 30-times faster than when it is made in the absence of added Mg2+. Addition of Mg2+ after phosphorylation is uneffective in accelerating the hydrolysis of phosphoenzyme even in solubilized enzyme, suggesting that phosphorylation of the Ca2+ pump results in occlusion of the site at which Mg2+ combines to accelerate the release of phosphate. 3. Occlusion of the site for Mg2+ can be partially reversed by trans-1,2-diaminocyclohexonetetraacetic acid (CDTA). Use was made of this property to demonstrate that for the rapid release of phosphate to occur Mg2+ has to be bound to the enzyme. 4. Results seem to indicate that Mg2+ combines with the Ca2+ pump prior to phosphorylation.

References

Jul 24, 1975·The Journal of Membrane Biology·A F Rega, P J Garrahan
Apr 16, 1973·Biochimica Et Biophysica Acta·G Meissner

Citations

Dec 1, 1987·Journal of Bioenergetics and Biomembranes·A G Lee
Oct 31, 1980·The Journal of Membrane Biology·V C Chiu, D H Haynes
Jun 8, 2001·The Biochemical Journal·A G Lee, J M East
Nov 1, 1979·Archives of Biochemistry and Biophysics·G L AlonsoS Terradas de Fermani
May 1, 1981·Archives of Biochemistry and Biophysics·M Chiesi, G Inesi
Nov 8, 1996·Biochimica Et Biophysica Acta·D Takara, G L Alonso
Jan 15, 1986·European Journal of Biochemistry·C R Fleschner, N Kraus-Friedmann
Jan 1, 1982·Annals of the New York Academy of Sciences·J T Penniston

Related Concepts

Acetic Acids
DNA-dependent ATPase
Adenosine Triphosphate, Chromium Ammonium Salt
Calcium
Cyclohexylamine
Hydrogen-Ion Concentration
Magnesium
Orthophosphate
Vigilon
Sarcoplasmic Reticulum

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