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Science 12 October 1990:
Vol. 250. no. 4978, pp. 285 - 288
DOI: 10.1126/science.2218533
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Articles

Science, Vol 250, Issue 4978, 285-288
Copyright © 1990 by American Association for the Advancement of Science

articles

A magnesium current in Paramecium

RR Preston

Laboratory of Molecular Biology, University of Wisconsin-Madison 53706.

Recent reappraisals of the role of ionized magnesium in cell function suggest that many cells maintain intracellular free Mg2+ at low concentrations (0.1 to 0.7 mM) and that external agents can influence cell function via changes in intracellular Mg2+ concentration. Depolarization and hyperpolarization of voltage-clamped Paramecium elicited a Mg2(+)-specific current, IMg. Both Co2+ and Mn2+ were able to substitute for Mg2+ as charge carriers, but the resultant currents were reduced compared with Mg2+ currents. Intracellular free Mg2+ concentrations were estimated from the reversal potential of IMg to be about 0.39 mM. The IMg was inhibited when external Ca2+ was removed or a Ca2+ chelator was injected, suggesting that its activation was Ca2(+)-dependent.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Genetic dissection of attractant-induced conductances in Paramecium.
W. E. Bell, R. R. Preston, J. Yano, and J. L. Van Houten (2007)
J. Exp. Biol. 210, 357-365
   Abstract »    Full Text »    PDF »
An exchanger-like protein underlies the large Mg2+ current in Paramecium.
W. J. Haynes, C. Kung, Y. Saimi, and R. R. Preston (2002)
PNAS 99, 15717-15722
   Abstract »    Full Text »    PDF »
Isolation and Characterization of Magbane, a Magnesium-Lethal Mutant of Paramecium.
J. A. Hammond and R. R. Preston (2001)
Genetics 158, 1061-1069
   Abstract »    Full Text »    PDF »
Overexpression of the Saccharomyces cerevisiae Magnesium Transport System Confers Resistance to Aluminum Ion.
C. W. MacDiarmid and R. C. Gardner (1998)
J. Biol. Chem. 273, 1727-1732
   Abstract »    Full Text »    PDF »


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Science. ISSN 0036-8075 (print), 1095-9203 (online)