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Calmodulin directly gates gap junction channels
C Peracchia1, A Sotkis, X G Wang
1Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, New York 14642-8711, USA. camilo_peracchia@urmc.rochester.edu
The Journal of Biological Chemistry
|June 15, 2000
Summary
Calmodulin directly regulates gap junction channel gating, influencing both chemical and voltage sensitivity. This protein interaction occurs before gap junction formation, revealing a key mechanism in cellular communication.
Area of Science:
- Cell Biology
- Biophysics
- Molecular Biology
Background:
- Cytosolic factors control gap junction channel gating through poorly understood mechanisms.
- Calmodulin's involvement in gap junction gating has been proposed but lacked definitive evidence.
Purpose of the Study:
- To investigate the direct role of calmodulin in the chemical and voltage gating of gap junction channels.
- To elucidate the mechanism and timing of calmodulin interaction with connexin 32.
Main Methods:
- Expression of a specific calmodulin mutant in cells expressing connexin 32.
- Immunofluorescence to detect calmodulin and connexin 32 localization.
- Analysis of gap junction channel gating sensitivity to chemical and voltage stimuli.
Main Results:
- Calmodulin is associated with gap junctions and directly influences chemical gating.
- A calmodulin mutant with altered Ca(2+) binding affinity increased chemical gating sensitivity and decreased voltage sensitivity.
- The observed effects were dependent on the mutant being expressed before connexin 32, indicating pre-formation interaction.
Conclusions:
- Calmodulin plays a direct role in the chemical gating of connexin 32 gap junction channels.
- Calmodulin interacts with connexin 32 prior to gap junction assembly, functioning as an integral regulatory subunit.
- This interaction is crucial for modulating gap junction channel function in response to cellular signals.
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