Reports

Phosphorylation-independent modulation of L-type calcium channels by magnesium-nucleotide complexes

Science  10 Jul 1992:
Vol. 257, Issue 5067, pp. 245-248
DOI: 10.1126/science.1321495

Abstract

Free magnesium ions and magnesium-nucleotide complexes can exert opposite effects on many fundamental cellular processes. Although increases in the intracellular concentration of magnesium ions inhibit the L-type calcium current in heart cells, magnesium-adenosine triphosphate complexes (MgATP) would be expected to increase the current by promoting channel phosphorylation. Rapid increases in the intracellular concentration of MgATP induced by flash photolysis of caged magnesium or caged ATP resulted in enhanced calcium current. The increase in calcium current was not prevented by blocking phosphorylation, revealing a previously unrecognized direct regulatory action of the magnesium-nucleotide complex.

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