Living synaptic vesicle marker: Synaptotagmin-GFP

Synapses are the site of chemical communication between neurons and between neurons and muscles. The synaptic vesicle (SV) is a prominent presynaptic organelle which contains chemical neurotransmitters and fuses with the plasma membrane to mediate neurotransmission. There are about 50 or so synaptic proteins which are either integral vesicle membrane proteins (e.g., synaptotagmin, syt; and synaptobrevin, syb) or vesicle-associated proteins (e.g., cysteine string protein, CSP). We have transformed Drosophila with a novel syt-eGFP (enhanced GFP) fusion protein, the fluorescence pattern of which colocalizes with native SV proteins at synapses, suggesting that the syt-eGFP fusion protein is correctly localized as an integral SV protein and therefore a good SV marker in living synapses. We demonstrate that the syt-eGFP line can be used to study SV dynamics in vivo by fluorescence recovery after photobleach (FRAP).