Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers

Bakhrom K. Berdiev, Ramon Latorre, Dale J. Benos, Iskander I. Ismailov

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Abstract

The mechanism by which the cytoskeletal protein actin affects the conductance of amiloride-sensitive epithelial sodium channels (ENaC) was studied in planar lipid bilayers. In the presence of monomeric actin, we found a decrease in the single-channel conductance of α-ENaC that did not occur when the internal [Ca2+]free was buffered to 2+ induced the appearance of long-lived closed intervals separating bursts of channel activity, both in the presence and in the absence of actin. In the absence of actin, the duration of these bursts and the time spent by the channel in its open, but not in its short-lived closed state, were inversely proportional to [Ca2+]. This, together with a lengthening of the interburst intervals, translated into a dose-dependent decrease in the single-channel open probability. In contrast, a [Ca2+]-dependent decrease in α-ENaC conductance in the presence of actin was accompanied by lengthening of the burst intervals with no significant changes in the open or closed (both short- and long-lived) times. We conclude that Ca2+ acts as a "fast-to-intermediate" blocker when monomeric actin is present, producing a subsequent attenuation of the apparent unitary conductance of the channel.

Original languageEnglish
Pages (from-to)2176-2186
Number of pages11
JournalBiophysical Journal
Volume80
Issue number5
Publication statusPublished - 2001
Externally publishedYes

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Epithelial Sodium Channels
Lipid Bilayers
Actins
Cytoskeletal Proteins

ASJC Scopus subject areas

  • Biophysics

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Berdiev, B. K., Latorre, R., Benos, D. J., & Ismailov, I. I. (2001). Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers. Biophysical Journal, 80(5), 2176-2186.

Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers. / Berdiev, Bakhrom K.; Latorre, Ramon; Benos, Dale J.; Ismailov, Iskander I.

In: Biophysical Journal, Vol. 80, No. 5, 2001, p. 2176-2186.

Research output: Contribution to journalArticle

Berdiev, BK, Latorre, R, Benos, DJ & Ismailov, II 2001, 'Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers', Biophysical Journal, vol. 80, no. 5, pp. 2176-2186.
Berdiev BK, Latorre R, Benos DJ, Ismailov II. Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers. Biophysical Journal. 2001;80(5):2176-2186.
Berdiev, Bakhrom K. ; Latorre, Ramon ; Benos, Dale J. ; Ismailov, Iskander I. / Actin modifies Ca2+ block of epithelial Na+ channels in planar lipid bilayers. In: Biophysical Journal. 2001 ; Vol. 80, No. 5. pp. 2176-2186.
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