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Published on: April 23, 2011
Contactin associates with Na+ channels and increases their functional expression
K Kazarinova-Noyes1, J D Malhotra, D P McEwen
1Departments of Neurobiology/Anatomy and Biochemistry/Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA.
Summary
Contactin, a surface glycoprotein, enhances neuronal sodium channel (Na+) function and surface density by interacting with the beta1 subunit. This interaction is crucial for Na+ channel distribution in both developing and adult nervous systems.
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- Contactin (F3, F11) is a cell surface glycoprotein with structural similarities to the beta2 subunit of voltage-gated sodium channels.
- Contactin and sodium channels have been observed to associate in brain homogenates, suggesting a functional complex.
Purpose of the Study:
- To investigate the functional interaction between contactin and voltage-gated sodium channels.
- To determine the specific subunits involved in the contactin-sodium channel complex.
- To examine the distribution of contactin and sodium channels in the central and peripheral nervous systems.
Main Methods:
- Co-immunoprecipitation assays to detect protein-protein interactions.
- Cell transfection experiments to measure sodium currents and saxitoxin binding.
- Immunocytochemical studies to visualize protein localization in neural tissues.
Main Results:
- Co-expression of contactin with Na(v)1.2alpha and beta1 sodium channel subunits significantly increased peak sodium currents and saxitoxin binding.
- Contactin specifically interacts with the beta1 subunit of sodium channels.
- Contactin and sodium channels show colocalization at nodes of Ranvier during development and remyelination in the CNS and PNS.
Conclusions:
- Contactin modulates the functional expression and surface density of voltage-gated sodium channels.
- The interaction between contactin and the beta1 subunit is key to this modulation.
- Contactin plays a significant role in the distribution of sodium channels in neurons, particularly at nodes of Ranvier.
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