Myelin-associated glycoprotein binding to gangliosides. Structural specificity and functional implications
R L Schnaar1, B E Collins, L P Wright
1Department of Pharmacology, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
Annals of the New York Academy of Sciences
|July 21, 1998
Summary
Myelin-associated glycoprotein (MAG) binds specifically to certain gangliosides, which are crucial for myelin-neuron interactions. This interaction is vital for nerve cell communication and function.
Area of Science:
- Neuroscience
- Molecular Biology
- Biochemistry
Background:
- Myelin-associated glycoprotein (MAG) mediates myelin-neuron interactions.
- MAG is a lectin that binds to sialylated glycoconjugates.
- Gangliosides are abundant sialylated glycoconjugates in the brain and potential neuronal ligands for MAG.
Purpose of the Study:
- To investigate the specific binding interactions between MAG and gangliosides.
- To determine the role of gangliosides in MAG-mediated myelin-neuron communication.
Main Methods:
- Engineered cells expressing MAG to test adhesion to various gangliosides.
- Modified ganglioside structures to identify key binding determinants.
- Compared MAG binding specificity with related immunoglobulin superfamily members (CD22, sialoadhesin).
- Enzymatically removed sialic acids from nerve cells to assess functional interaction changes with myelin.
Main Results:
- MAG specifically adhered to gangliosides with alpha 2,3-linked N-acetylneuraminic acid, with GQ1b alpha showing the highest affinity.
- MAG binding was dependent on the N-acetylneuraminic acid moiety, including its carboxylic acid, hydroxyl, and N-acetyl groups.
- MAG exhibited more stringent ganglioside binding specificity than sialoadhesin and CD22.
- Sialic acid removal from nerve cells altered their interaction with myelin.
Conclusions:
- Gangliosides are key functional neuronal ligands for MAG.
- The specific binding of MAG to gangliosides plays a significant role in myelin-neuron interactions.
- Understanding these interactions is crucial for comprehending neural development and function.
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