title: Traffic of dynamin within individual Drosophila synaptic boutons relative to compartment-specific markers.
abstract: Presynaptic terminals contain several specialized compartments, which have been described by electron microscopy. We show in an identified Drosophila neuromuscular synapse that several of these compartments-synaptic vesicle clusters, presynaptic plasma membrane, presynaptic cytosol, and axonal cytoskeleton-labeled by specific reagents may be resolved from one another by laser scanning confocal microscopy. Using a panel of compartment-specific markers and Drosophila shibire(ts1) mutants to trap an intermediate stage in synaptic vesicle recycling, we have examined the localization and redistribution of dynamin within single synaptic varicosities at the larval neuromuscular junction. Our results suggest that dynamin is not a freely diffusible molecule in resting nerve terminals; rather, it appears localized to synaptic sites by association with yet uncharacterized presynaptic components. In shi(ts1) nerve terminals depleted of synaptic vesicles, dynamin is quantitatively redistributed to the plasma membrane. It is not, however, distributed uniformly over presynaptic plasmalemma; instead, fluorescence images show "hot spots" of dynamin on the plasma membrane of vesicle-depleted nerve terminals. We suggest that these dynamin-rich domains may mark the active zones for synaptic vesicle endocytosis first described at the frog neuromuscular junction.
authors: Department of Molecular and Cellular Biology, University of Arizona, Tucson 85721, USA.
authors: P S
authors: PS
authors: Estes
authors: J
authors: J
authors: Roos
authors: A
authors: A
authors: van der Bliek
authors: R B
authors: RB
authors: Kelly
authors: K S
authors: KS
authors: Krishnan
authors: M
authors: M
authors: Ramaswami
mesh_terms: D000818:Animals; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D002462:Cell Membrane / Q000378:metabolism; D004330:Drosophila / Q000033:anatomy & histology / Q000378:metabolism; D029721:Drosophila Proteins; D034281:Dynamins; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D007814:Larva / Q000648:ultrastructure; D008562:Membrane Glycoproteins / Q000378:metabolism; D009411:Nerve Endings / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000378:metabolism; D017729:Presynaptic Terminals / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism*; D050857:Synaptotagmins; D013696:Temperature
chemical_list: D015415:Biomarkers; D002135:Calcium-Binding Proteins; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D050857:Synaptotagmins; D020558:GTP Phosphohydrolases; D034281:Dynamins; C439628:shi protein, Drosophila