Study Defines Synaptic Role of Alpha-Neurexin

A recent study describes the functional activity of the alpha-neurexin protein family, which is essential for proper transmission of nervous impulses through their ability to organize presynaptic calcium channels.

Neurexins are a large family of proteins that act as neuronal cell-surface receptors. The function and localization of the various neurexins, however, have not yet been clarified. In a paper published in the June 26, 2003, issue of Nature, researchers at the University of Texas Southwestern Medical Center (Dallas, USA) describe the use of triple knockout mice to determine the role of alpha-neurexin in organizing the synapses for transfer of information from the neurons.

They showed that alpha-neurexin was not required for synapse formation, but was essential for calcium-triggered neurotransmitter release. In the knockout mice neurotransmitter release was impaired because synaptic calcium channel function was markedly reduced, although the number of cell-surface calcium channels appeared normal.

"The results from this study were a big surprise,” said senior author Dr. Thomas Südhof, director of both the Center for Basic Neuroscience and the C. Vincent Prothro Center for Research in Basic Neuroscience at the University of Texas Southwestern Medical Center. "When we originally described alpha-neurexin almost 10 years ago, we hypothesized that the proteins would be involved in signaling the synapses. We thought of it more in terms of the formation of the synapses. The surprise is that it turns out not to be involved in the formation of synapses but what happens subsequently to activate synapses.”




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University of Texas Southwestern Medical Center