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Science 21 September 1990:
Vol. 249. no. 4975, pp. 1441 - 1444
DOI: 10.1126/science.2169650
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Articles

Science, Vol 249, Issue 4975, 1441-1444
Copyright © 1990 by American Association for the Advancement of Science

articles

Calmodulin activation of calcium-dependent sodium channels in excised membrane patches of Paramecium

Y Saimi and KY Ling

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

Calmodulin is a calcium-binding protein that participates in the transduction of calcium signals. The electric phenotypes of calmodulin mutants of Paramecium have suggested that the protein may regulate some calcium-dependent ion channels. Calcium-dependent sodium single channels in excised patches of the plasma membrane from Paramecium were identified, and their activity was shown to decrease after brief exposure to submicromolar concentrations of calcium. Channel activity was restored to these inactivated patches by adding calmodulin that was isolated from Paramecium to the cytoplasmic surface. This restoration of channel activity did not require adenosine triphosphate and therefore, probably resulted from direct binding of calmodulin, either to the sodium channel itself or to a channel regulator that was associated with the patch membrane.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
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An exchanger-like protein underlies the large Mg2+ current in Paramecium.
W. J. Haynes, C. Kung, Y. Saimi, and R. R. Preston (2002)
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Calmodulin Mediates Calcium-dependent Activation of the Intermediate Conductance Channel, IKCa1.
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