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Disulfide-mediated dimerization of L1 Ig domains
J Haspel1, G Schürmann, J Jacob
1W.M. Keck Center for Collaborative Neuroscience, Rutgers University, Piscataway, New Jersey 08854-8082, USA.
Journal of Neuroscience Research
|December 18, 2001
Summary
The neural cell adhesion molecule L1
Area of Science:
- Neuroscience
- Molecular Biology
- Cell Biology
Background:
- The neural cell adhesion molecule L1 (L1) is crucial for central nervous system (CNS) development.
- Its extracellular immunoglobulin-like (Ig) domains mediate homophilic binding and neurite outgrowth.
- Understanding L1 conformation is key to correlating its structure with biological function.
Purpose of the Study:
- To investigate the structural conformations of L1-Fc fusion proteins and L1 fragments.
- To correlate these structures with previously characterized bioactivities.
- To elucidate the role of L1 domain interactions in its function.
Main Methods:
- Rotary shadowing electron microscopy was used to analyze L1-Fc fusion proteins and L1 fragments.
- L1-GFP fusion proteins were analyzed for cell surface dimerization.
- Disulfide bond analysis was performed.
Main Results:
- Bioactive L1-Fc proteins (Ig domains 1-4 or 1-6) showed extended, branched structures.
- Inactive L1-Fc proteins (Ig domains 1-3) adopted compact shapes, suggesting intermolecular interactions.
- L1 fragments and cell surface L1 proteins exhibited disulfide-mediated dimerization, particularly with fewer Ig domains.
Conclusions:
- L1 conformation is directly linked to its biological activity.
- Disulfide-mediated dimerization of L1, especially involving the N-terminal Ig domains, represents a novel regulatory mechanism.
- Mutations affecting L1 dimerization could impair its function in CNS development.
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