Synaptotagmin-syntaxin interaction: the C2 domain as a Ca2+-dependent electrostatic switch.

Synaptotagmin I is a synaptic vesicle protein that is thought to act as a Ca2+ sensor in neurotransmitter release. The first C2 domain of synaptotagmin I (C2A domain) contains a bipartite Ca2+-binding motif and interacts in a Ca2+-dependent manner with syntaxin, a central component of the membrane fusion complex. Analysis ...
by nuclear magnetic resonance spectroscopy and site-directed mutagenesis shows that this interaction is mediated by the cooperative action of basic residues surrounding the Ca2+-binding sites of the C2A domain and is driven by a change in the electrostatic potential of the C2A domain induced by Ca2+ binding. A model is proposed whereby synaptotagmin acts as an electrostatic switch in Ca2+-triggered synaptic vesicle exocytosis, promoting a structural rearrangement in the fusion machinery that is effected by its interaction with syntaxin.
Mesh Terms:
Amino Acid Sequence, Animals, Binding Sites, Calcium, Calcium-Binding Proteins, Circular Dichroism, Glutathione Transferase, Magnetic Resonance Spectroscopy, Membrane Fusion, Membrane Glycoproteins, Membrane Proteins, Models, Molecular, Mutagenesis, Site-Directed, Nerve Tissue Proteins, Point Mutation, Protein Conformation, Protein Denaturation, Protein Structure, Secondary, Qa-SNARE Proteins, Recombinant Fusion Proteins, Static Electricity, Synaptotagmin I, Synaptotagmins, Thermodynamics
Neuron
Date: Jan. 01, 1997
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