Syntaxin 1A interacts with multiple exocytic proteins to regulate neurotransmitter release in vivo. |
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Authors: | M N Wu T Fergestad T E Lloyd Y He K Broadie H J Bellen |
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Institution: | Department of Cell Biology, Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA. |
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Abstract: | Biochemical studies suggest that syntaxin 1A participates in multiple protein-protein interactions in the synaptic terminal, but the in vivo significance of these interactions is poorly understood. We used a targeted mutagenesis approach to eliminate specific syntaxin binding interactions and demonstrate that Drosophila syntaxin 1A plays multiple regulatory roles in neurotransmission in vivo. Syntaxin mutations that eliminate ROP/Munc-18 binding display increased neurotransmitter release, suggesting that ROP inhibits neurosecretion through its interaction with syntaxin. Syntaxin mutations that block Ca2+ channel binding also cause an increase in neurotransmitter release, suggesting that syntaxin normally functions in inhibiting Ca2+ channel opening. Additionally, we identify and characterize a syntaxin Ca2+ effector domain, which may spatially organize the Ca2+ channel, cysteine string protein, and synaptotagmin for effective excitation-secretion coupling in the presynaptic terminal. |
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