Vesicular release of transmitter at active zones

Published on December 2, 2014   29 min
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My name is Stefan Hallermann. I'm a professor at the Carl-Ludwig-Institute of Physiology at the University of Leipzig in Germany. You've selected the Henry Stewart talk about vesicular release of transmitter at active zones.
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To communicate with each other, neurons can use chemical synaptic transmission. The enlargement shows a schematic illustration of an electron microscopic image of such a chemical synapse. Upon the arrival of an action potential in the presynaptic terminal illustrated by the red arrow, voltage-dependent calcium channels open, and the influx of calcium triggers the fusion of transmitter-filled synaptic vesicles. As a consequence, the transmitter illustrated by red triangles diffuses through the synaptic cleft to the postsynaptic receptors, which finally elicits an electrical signal in the postsynaptic cell. The enlargement shows the double lipid membrane of the vesicle and the presynaptic plasma membrane. The SNARE proteins, synaptobrevin, SNAP-25, and syntaxin, are involved in the fusion of these two double lipid membranes, which finally elicits the release of neurotransmitter. The binding of calcium to the vesicular protein, synaptotagmin, is involved in triggering this fusion. As shown in the enlargement of a synaptic vesicle, the protein composition of the vesicle is already quite well understood. In contrast, the organization of the proteins at the presynaptic plasma membrane that built the active zone is less well understood. This protein network is also referred to as the cytomatrix at the active zone. In the here shown example of a central synapse, the cytomatrix appears as a triangular, grid-like array. The shape of the cytomatrix can be very different depending on on the type of synapse, as shown in the next slide.
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Vesicular release of transmitter at active zones

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