The synaptotagmins: calcium sensors for vesicular trafficking.
The synaptotagmin family of vesicle proteins is believed to mediate calcium-dependent regulation of membrane trafficking. Detailed biochemical and in vivo studies of the most characterized isoform, synaptotagmin 1 (syt 1), have provided compelling evidence that it functions as a calcium sensor for fast neurotransmitter release at synapses. However, the function of the remaining isoforms is unclear, and multiple roles have been hypothesized for several of these. Recent evidence in Drosophila has given insight into the function of some of the remaining synaptotagmin family members. Of the five evolutionarily conserved isoforms in Drosophila, only two, syt 1 and syt 4, localize to most, if not all, synapses. The former is localized to presynaptic terminals, whereas the latter is predominantly postsynaptic. This suggests an intriguing possibility that syt 4 may mediate a postsynaptic vesicle trafficking pathway, providing a molecular basis for an evolutionarily conserved bidirectional vesicular trafficking communication system at synapses.
Yoshihara
Motojiro
M
The Picower Center for Learning and Memory, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. motojiro@mit.edu
Montana
Enrico Sakai
ES
D000818:Animals; D020013:Calcium Signaling / Q000502:physiology*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster; D006801:Humans; D008561:Membrane Fusion / Q000502:physiology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009420:Nervous System / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D013572:Synaptic Vesicles / Q000378:metabolism* / Q000648:ultrastructure; D050863:Synaptotagmin I; D050857:Synaptotagmins
D002135:Calcium-Binding Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; C494310:SYT1 protein, human; D050863:Synaptotagmin I; D050857:Synaptotagmins