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Modulation of the slow/common gating of CLC channels by intracellular cadmium.

Yu Y, Tsai MF, Yu WP, Chen TY - J. Gen. Physiol. (2015)

Bottom Line: Here, we found that intracellularly applied Cd(2+) reduces the current of CLC-0 because of its inhibition on the slow gating.Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0.The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd(2+) likely depends on their alteration of subunit interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618.

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Steady-state inhibition of the I225W/V490W mutant of CLC-0 by intracellular Cd2+. (A) Original recording traces in the absence of Cd2+ (control) and in the presence of various [Cd2+]. (B) Voltage-dependent activation curves of I225W/V490W in 0 (control) and various [Cd2+] based on the experiments similar to those shown in A. The initial tail current was normalized to that obtained after the test pulse of −160 mV in the absence of Cd2+. Notice that the maximal Po of I225W/V490W is reduced at 1 mM of Cd2+. (C) Dose–response curves of the Cd2+ inhibition of I225W/V490W at different voltages (black, −80 mV; blue, −120 mV; red, −160 mV). Data points were fitted to a Langmuir equation with an apparent affinity of 1 µM (−80 mV), 7 µM (−120 mV), and 204 µM (−160 mV), respectively.
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fig5: Steady-state inhibition of the I225W/V490W mutant of CLC-0 by intracellular Cd2+. (A) Original recording traces in the absence of Cd2+ (control) and in the presence of various [Cd2+]. (B) Voltage-dependent activation curves of I225W/V490W in 0 (control) and various [Cd2+] based on the experiments similar to those shown in A. The initial tail current was normalized to that obtained after the test pulse of −160 mV in the absence of Cd2+. Notice that the maximal Po of I225W/V490W is reduced at 1 mM of Cd2+. (C) Dose–response curves of the Cd2+ inhibition of I225W/V490W at different voltages (black, −80 mV; blue, −120 mV; red, −160 mV). Data points were fitted to a Langmuir equation with an apparent affinity of 1 µM (−80 mV), 7 µM (−120 mV), and 204 µM (−160 mV), respectively.

Mentions: A full characterization of the Cd2+ sensitivity of I225W/V490W is shown in Fig. 5 A, in which the currents of the mutant channel in excised membrane patches were recorded in various Cd2+ concentrations ([Cd2+]). We noticed that Cd2+ appears to have two distinct effects. First, the voltage-dependent steady-state activation curve of this mutant shifts to more hyperpolarized voltages in low [Cd2+] (<30 µM). Second, higher [Cd2+] (such as 1 mM) reduces the maximal level of the channel activation (Fig. 5 B). Because of the dual effects of Cd2+, the dose–response curve of the Cd2+ inhibition throughout the entire Cd2+ concentration range cannot be fitted to a single Langmuir function. We thus focused on the inhibition by low [Cd2+] (up to 300 µM), and normalized the inhibition effect to that induced by 1 mM Cd2+. The values of IC50 so obtained were 1, 7, and 204 µM at −80, −120, and −160 mV, respectively (Fig. 5 C). Therefore, the inhibition of I225W/V490W by Cd2+ is voltage dependent; the apparent affinity is decreased with more hyperpolarized membrane potentials.


Modulation of the slow/common gating of CLC channels by intracellular cadmium.

Yu Y, Tsai MF, Yu WP, Chen TY - J. Gen. Physiol. (2015)

Steady-state inhibition of the I225W/V490W mutant of CLC-0 by intracellular Cd2+. (A) Original recording traces in the absence of Cd2+ (control) and in the presence of various [Cd2+]. (B) Voltage-dependent activation curves of I225W/V490W in 0 (control) and various [Cd2+] based on the experiments similar to those shown in A. The initial tail current was normalized to that obtained after the test pulse of −160 mV in the absence of Cd2+. Notice that the maximal Po of I225W/V490W is reduced at 1 mM of Cd2+. (C) Dose–response curves of the Cd2+ inhibition of I225W/V490W at different voltages (black, −80 mV; blue, −120 mV; red, −160 mV). Data points were fitted to a Langmuir equation with an apparent affinity of 1 µM (−80 mV), 7 µM (−120 mV), and 204 µM (−160 mV), respectively.
© Copyright Policy - openaccess
Related In: Results  -  Collection

License 1 - License 2
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getmorefigures.php?uid=PMC4664824&req=5

fig5: Steady-state inhibition of the I225W/V490W mutant of CLC-0 by intracellular Cd2+. (A) Original recording traces in the absence of Cd2+ (control) and in the presence of various [Cd2+]. (B) Voltage-dependent activation curves of I225W/V490W in 0 (control) and various [Cd2+] based on the experiments similar to those shown in A. The initial tail current was normalized to that obtained after the test pulse of −160 mV in the absence of Cd2+. Notice that the maximal Po of I225W/V490W is reduced at 1 mM of Cd2+. (C) Dose–response curves of the Cd2+ inhibition of I225W/V490W at different voltages (black, −80 mV; blue, −120 mV; red, −160 mV). Data points were fitted to a Langmuir equation with an apparent affinity of 1 µM (−80 mV), 7 µM (−120 mV), and 204 µM (−160 mV), respectively.
Mentions: A full characterization of the Cd2+ sensitivity of I225W/V490W is shown in Fig. 5 A, in which the currents of the mutant channel in excised membrane patches were recorded in various Cd2+ concentrations ([Cd2+]). We noticed that Cd2+ appears to have two distinct effects. First, the voltage-dependent steady-state activation curve of this mutant shifts to more hyperpolarized voltages in low [Cd2+] (<30 µM). Second, higher [Cd2+] (such as 1 mM) reduces the maximal level of the channel activation (Fig. 5 B). Because of the dual effects of Cd2+, the dose–response curve of the Cd2+ inhibition throughout the entire Cd2+ concentration range cannot be fitted to a single Langmuir function. We thus focused on the inhibition by low [Cd2+] (up to 300 µM), and normalized the inhibition effect to that induced by 1 mM Cd2+. The values of IC50 so obtained were 1, 7, and 204 µM at −80, −120, and −160 mV, respectively (Fig. 5 C). Therefore, the inhibition of I225W/V490W by Cd2+ is voltage dependent; the apparent affinity is decreased with more hyperpolarized membrane potentials.

Bottom Line: Here, we found that intracellularly applied Cd(2+) reduces the current of CLC-0 because of its inhibition on the slow gating.Our experimental results suggest that mutations of the corresponding residues in CLC-0 change the subunit interaction and alter the slow gating of CLC-0.The effect of these mutations on modulations of slow gating of CLC channels by intracellular Cd(2+) likely depends on their alteration of subunit interactions.

View Article: PubMed Central - HTML - PubMed

Affiliation: Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618 Center for Neuroscience and Department of Neurology, University of California, Davis, Davis, CA 95618.

No MeSH data available.


Related in: MedlinePlus