Opposite Cx32 and Cx26 Voltage-Gating Response to CO2 Reflects Opposite Voltage-Gating Polarity

Opposite Cx32 and Cx26 Voltage-Gating Response to CO2 Reflects Opposite Voltage-Gating Polarity Previous studies have shown that the V j-dependent gating behavior of gap junction channels is altered by CO2 exposure. V j-dependent channel closure is increased by CO2 in some connexin channels and decreased in others. Since the former type of channels gate on the relatively negative side by V j (negative gaters) and the latter at the positive side (positive gaters), it has been hypothesized that gating polarity determines the way CO2 affects V j closure. To test this hypothesis, we have studied the CO2-mediated changes in V j gating in channels made of Cx32, Cx26, or a Cx32 mutant (Cx32-N2D) in which asparagine (N) at position 2 was replaced with aspartate (D). With exposure to CO2, Cx32 channels (negative gaters) show increased V j-dependent closure, whereas Cx26 channels (positive gaters) respond in the opposite way to V j. Additionally, Cx32-N2D channels (positive gaters) show decreased V j closure with exposure to CO2. The reciprocal Cx26 mutant, Cx26-D2N (negative gater), could not be tested because it did not express functional homotypic channels. The data support the hypothesis that polarity of fast V j gating determines whether CO2 increases or decreases the V j dependent closure of gap junction channels. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Opposite Cx32 and Cx26 Voltage-Gating Response to CO2 Reflects Opposite Voltage-Gating Polarity

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Publisher
Springer-Verlag
Copyright
Copyright © 2004 by Springer Science+Business Media, Inc.
Subject
Life Sciences; Human Physiology; Biochemistry, general
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-004-0727-2
Publisher site
See Article on Publisher Site

Abstract

Previous studies have shown that the V j-dependent gating behavior of gap junction channels is altered by CO2 exposure. V j-dependent channel closure is increased by CO2 in some connexin channels and decreased in others. Since the former type of channels gate on the relatively negative side by V j (negative gaters) and the latter at the positive side (positive gaters), it has been hypothesized that gating polarity determines the way CO2 affects V j closure. To test this hypothesis, we have studied the CO2-mediated changes in V j gating in channels made of Cx32, Cx26, or a Cx32 mutant (Cx32-N2D) in which asparagine (N) at position 2 was replaced with aspartate (D). With exposure to CO2, Cx32 channels (negative gaters) show increased V j-dependent closure, whereas Cx26 channels (positive gaters) respond in the opposite way to V j. Additionally, Cx32-N2D channels (positive gaters) show decreased V j closure with exposure to CO2. The reciprocal Cx26 mutant, Cx26-D2N (negative gater), could not be tested because it did not express functional homotypic channels. The data support the hypothesis that polarity of fast V j gating determines whether CO2 increases or decreases the V j dependent closure of gap junction channels.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jan 1, 2004

References

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